Home » Public Forums » GMCnet » [GMCnet] GMCer stuck
| [GMCnet] GMCer stuck [message #176939] |
Mon, 16 July 2012 16:56  |
Tim Conway
Messages: 412
Registered: September 2005
Location: Long Island, New York
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I just received a call from a fairly new GMCer who called me a few months ago (from the Black List) to introduce himself. Took a ride in his coach and Richard is a very nice guy.
He just called a few minutes ago that he was starting out to a rally(?) and the coach maybe stuttered a little and died going through a busy intersection. He called Coach Net (I think) and they were saying a ground issue. He mentioned there is much added on wiring and he does have Fuel Injection.
Is there a logical sequence of suggested things to check regarding grounding or other things? Seems to be electric in nature rather than fuel. I will look through my notes after I post this as I seem to recall saving something about grounding.
Any help is much appreciated.
Tim Conway
LI NY 78 PB
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| Re: [GMCnet] GMCer stuck [message #176943 is a reply to message #176939] |
Mon, 16 July 2012 17:12  |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
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Here's the best troubleshooting guide I've found (it's at http://www.gmcmotorhome.info/engine.html)...
Hot To Test a HEI distributor(9/17/06)
Engine Cranks But Will Not Start
Turn the ignition off, remove the air cleaner, and look down the front carburetor barrels. Depress the accelerator once or twice while looking for gasoline squirting into the front barrels.
Gasoline present: go to Step 1
Gasoline not present: Fix missing gasoline problem.
1. With the ignition on, connect a voltmeter (or test light) to the + post or HEI BAT terminal located on the distributor cap.
+12 volts or Test LIGHT ON: Go to step 3.
No voltage or Test LIGHT OFF: Go to step 2.
2. Check for continuity or voltage drop in the ignition switch and in the circuit from the switch to HEI BAT terminal. Fix missing +12 volt problem.
STARTS: Stop—you’ve found the problem.
NO START: Go to step 3.
3. Remove a spark plug wire and insert a HEI spark tester ($2.99 from Harbor Freight) in line. Crank the engine and observe the light in the tester.
3a. Alternatively remove a spark plug wire and insert a metallic extension in the end of the wire. Using insulated pliers, hold the spark plug wire no more than .25 inch away from the engine block while cranking the engine. If you use the alternate method be very careful to hold the wire no more than .25 inch away from the engine. Greater distances can cause damage to the ignition module.
LIGHT FLASH IN TESTER or SPARK JUMP TO ENGINE BLOCK: The problem is not the ignition system. Check the fuel system, spark plugs, timing, and internal engine condition.
No light or NO SPARK: Go to step 4.
4. Remove and inspect the distributor cap for cracks and carbon-tracking. Visually inspect the distributor mechanism for moisture, corrosion, or burns. Repair as needed.
STARTS: Stop—you’ve fixed it.
NO START: Go to step 5.
5. Set an ohmmeter to the low scale. Connect the leads across the HEI’s “BAT” and “TACH” terminals.
ABOVE 1 OHM: Replace coil. If vehicle still doesn’t start, go to step 6.
0-1 OHM: Go to step 6.
6. Connect one ohmmeter lead to the “BAT” terminal and the other lead to the coil contact in the inside-center of the cap. Switch the first lead to the “TACH” terminal and recheck.
EITHER TEST READS 6K to 30K: Coil is OK. Go to Step 11.
BOTH TESTS READ INFINITY: Replace the coil. If the engine still won’t start, go to step 7.
7. Remove the green and white leads from the HEI control module. Connect the ohmmeter from ground to either lead.
INFINITE reading: Go to step 8.
LESS THAN INFINITY: Replace the pickup coil. If the engine still won’t start, replace the module.
8. Connect the ohmmeter across the green and white pick up coil leads.
READS 500-1,500 OHMS: Repeat Steps 7 and 8 while moving the vacuum advance with a screwdriver. If reading is still OK, replace the module.
DOES NOT READ 500-1,500 OHMS: Replace pickup coil. If the engine still doesn’t start, replace the module.
That is it. You will notice that there is really no diagnosis of the module. When everything else reads correct the module is replaced by default. In my case the coil read open. replacing it did not fix the problem so I had to replace the module also. BOTH items were bad and I assume the coil took out the module. HTH Ken B.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] GMCer stuck [message #176944 is a reply to message #176939] |
Mon, 16 July 2012 17:12 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Tim,
The first step is to determine whether the problem is fuel or electricity.
With EFI, checking fuel is easy: Remove the cover from the air cleaner and
watch down the TBI throat for fuel spray while cranking. If there is
spray, then the EFI is probably not the problem. If not, there's a whole
series of tests to do -- the EFI section of Howell's installation manual
(extracted from GM manuals) is quite good.
If the EFI is not the problem then the ignition probably is. The easiest
way to check that is with a spark indicator (which, at $2.99 from HF, I
think EVERYONE should carry) inserted in any spark plug lead at the
distributor or at a plug. It should flash as the engine turns. Not
flashing is a bad thing! Grounding of the distributor to the block, a bad
ignition module, a bad coil (or connection inside the distributor cap), or
a bad pickup coil are probably the most common failures.
HTH,
Ken H.
On Mon, Jul 16, 2012 at 5:56 PM, Tim Conway wrote:
> I just received a call from a fairly new GMCer who called me a few months
> ago (from the Black List) to introduce himself. Took a ride in his coach
> and Richard is a very nice guy.
>
> He just called a few minutes ago that he was starting out to a rally(?)
> and the coach maybe stuttered a little and died going through a busy
> intersection. He called Coach Net (I think) and they were saying a ground
> issue. He mentioned there is much added on wiring and he does have Fuel
> Injection.
>
> Is there a logical sequence of suggested things to check regarding
> grounding or other things? Seems to be electric in nature rather than fuel.
> I will look through my notes after I post this as I seem to recall saving
> something about grounding.
> ...
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] GMCer stuck [message #176951 is a reply to message #176939] |
Mon, 16 July 2012 19:06 |
bryant374
Messages: 563
Registered: May 2004
Location: Pleasant Valley, NY 12569
Karma: 1
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Richard called me a couple of times. At first his description sounded like a bad battery/electrical connection. He got a short run & nearly got in a Home Depot parking lot he was trying for. He has a mechanic lined up for the morning, I suggested he get a gas filter and check fuel lines. Tank switch and battery boost makes no difference. The coach has some nice updates but since he has only owned it for a couple of months most history is unknown to him.
Bill Bryant
PO 1976~PB (owned 34 years)
1914 Ford (owned 70 years)
1965 Corvette (owned 39 years)
GMC Motorhome History
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| Re: [GMCnet] GMCer stuck [message #176959 is a reply to message #176952] |
Mon, 16 July 2012 19:42 |
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ljdavick
Messages: 3548
Registered: March 2007
Location: Fremont, CA
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That's a good place to rest and check things out.
If it's fuel related I'd do for the easy things first like fuel filter, loose connections, and blown fuses. I know that my electric fuel pump would take a siesta without my permission from time to time 'till I cleaned up the connections.
If it's spark, and the distributor is still turning, then the easy suspects are module or coil.
I'd trade my day at work to be on the road in a broken-down GMC!
Larry Davick
Fremont, California
A Mystery Machine
'76 (ish) Palm Beach
----- Original Message -----
From: "Tim Conway" <mactac735@mac.com>
To: gmclist@temp.gmcnet.org
Sent: Monday, July 16, 2012 5:06:50 PM
Subject: Re: [GMCnet] GMCer stuck
It looks like Richard is being towed to a Home Depot parking lot for the night. I'm trying to get a local mechanic to come to him tomorrow.
Tim Conway
LI NY 78 PB
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Larry Davick
A Mystery Machine
1976(ish) Palm Beach
Fremont, Ca
Howell EFI + EBL + Electronic Dizzy
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| Re: [GMCnet] GMCer stuck [message #177025 is a reply to message #176959] |
Tue, 17 July 2012 12:29 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
Karma: 3
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On a related note, I'm in the process of putting together the spares kit for my newly-acquired Royale, and have looked through the documents and online, but haven't found the details I need.
1) What is the Delco part number for the ignition module?
2) What is the Delco part number for the coil (or would a "generic coil" work - I have one of those sitting around)?
3) What is the Delco part number for the distributor cap?
The suggested spares list includes a rotor - I'm wondering if this is really necessary (I did have a rotor stop me once, but it was a Fiat rotor with a resistor in it that burnt out... AFAIK, the GMC rotor is just a metal strip connected to the "button").
And while not really a "spare" (heaven help me if I need this on the road!) what's the right part number for the Edelbrock Performer intake manifold - is it the 2711, 3711, or 7111?
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] GMCer stuck [message #177027 is a reply to message #177025] |
Tue, 17 July 2012 12:43 |
emerystora
Messages: 4442
Registered: January 2004
Karma: 13
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Yes, you should also carry a rotor. I had one go bad once and the spark would not go to the terminals.
Any of the HEI coils will work but you should be aware that some are wound the opposite direction. Your pickup coil and your main coil should be the same polarity for best preform acne. You can read about it here:
http://gmcws.org/Tech/dsimmons/ignition/ignition.html
I don't have the parts numbers right in front of me and I am using my iPhone to reply. I suggest that you join GMCMI and you will get a parts book that will have all the numbers you need.
Plus the other benefits of membership
www. GMCMI.com
Emery Stora
77 Kingsley
Frederick, CO
On Jul 17, 2012, at 11:29 AM, Mark <mark@habcycles.com> wrote:
>
>
> On a related note, I'm in the process of putting together the spares kit for my newly-acquired Royale, and have looked through the documents and online, but haven't found the details I need.
>
> 1) What is the Delco part number for the ignition module?
> 2) What is the Delco part number for the coil (or would a "generic coil" work - I have one of those sitting around)?
> 3) What is the Delco part number for the distributor cap?
>
> The suggested spares list includes a rotor - I'm wondering if this is really necessary (I did have a rotor stop me once, but it was a Fiat rotor with a resistor in it that burnt out... AFAIK, the GMC rotor is just a metal strip connected to the "button").
>
> And while not really a "spare" (heaven help me if I need this on the road!) what's the right part number for the Edelbrock Performer intake manifold - is it the 2711, 3711, or 7111?
> --
> Mark Hickey
> Mesa, AZ
> 1978 Royale Center Kitchen
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
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| Re: [GMCnet] GMCer stuck [message #177052 is a reply to message #177025] |
Tue, 17 July 2012 16:39 |
Mr ERFisher
Messages: 7117
Registered: August 2005
Karma: 2
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module
http://www.gmcmhphotos.com/photos/gmc-chemicals-and-tools/p37219-delco-igniton-module.html
gene
On Tue, Jul 17, 2012 at 10:29 AM, Mark <mark@habcycles.com> wrote:
>
>
> On a related note, I'm in the process of putting together the spares kit
> for my newly-acquired Royale, and have looked through the documents and
> online, but haven't found the details I need.
>
> 1) What is the Delco part number for the ignition module?
> 2) What is the Delco part number for the coil (or would a "generic coil"
> work - I have one of those sitting around)?
> 3) What is the Delco part number for the distributor cap?
>
> The suggested spares list includes a rotor - I'm wondering if this is
> really necessary (I did have a rotor stop me once, but it was a Fiat rotor
> with a resistor in it that burnt out... AFAIK, the GMC rotor is just a
> metal strip connected to the "button").
>
> And while not really a "spare" (heaven help me if I need this on the
> road!) what's the right part number for the Edelbrock Performer intake
> manifold - is it the 2711, 3711, or 7111?
> --
> Mark Hickey
> Mesa, AZ
> 1978 Royale Center Kitchen
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://temp.gmcnet.org/cgi-bin/mailman/listinfo/gmclist
>
--
Gene Fisher -- 74-23,77PB/ore/ca
“Give a man a fish; you have fed him for today --- give him a URL and
-------
http://gmcmotorhome.info/
Alternator Protection Cable
http://gmcmotorhome.info/APC.html
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| Re: [GMCnet] GMCer stuck [message #177141 is a reply to message #177066] |
Wed, 18 July 2012 10:44 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
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My money's on it being a vapor lock issue. If so, it probably will go away if he only drives it when it's cooler, and stays away from stop and go traffic. I can't think of a worse case scenario than getting vapor lock on one of the NYC bridges in rush hour on a really hot day. I've only ever had one very brief vapor lock issue (though it was about 110 in AZ), and that was only because I hadn't turned on the supplemental fuel pump that a previous owner was nice enough to install. I hit the switch and was back underway with no drama.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] GMCer stuck [message #177149 is a reply to message #177143] |
Wed, 18 July 2012 11:14 |
habbyguy
Messages: 896
Registered: May 2012
Location: Mesa, AZ
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| Mr ERFisher wrote on Wed, 18 July 2012 08:51 |
So. I am wondering.
Why not run the high volume pump all the time so this will never happen and it is all automatic. ?
Every new vehicle in the world does this
JWID
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The pump was installed with a lighted toggle switch on the dash, so it's easy enough to turn on or off. I guess I don't worry too much about needing it, given that my coach didn't exhibit any tendency toward vapor lock until the conditions were REALLY bad (stop and go traffic at 110 degrees ambient, so higher than that on the sun-drenched road). I drove the rig back from west LA when I bought it, and spent a couple hours in stop-and-go LA rush hour traffic (something I wouldn't recommend, BTW), and then across eastern CA and most of AZ in really hot (100+) sunny conditions. At the time, I wasn't even aware there WAS an electric fuel pump installed (or a vacuum pump, which is operated by another switch right beside the one for the fuel pump).
In the end, I guess I figure that the carb is designed for the fuel pressure supplied by the mechanical pump alone, and that I really like having the extra control. Also, electric fuel pumps DO wear out, so I suppose I'm saving money not using it when it's not really needed.
Mark Hickey
Mesa, AZ
1978 Royale Center Kitchen
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| Re: [GMCnet] GMCer stuck [message #177188 is a reply to message #177143] |
Wed, 18 July 2012 14:39 |
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mike miller
Messages: 3576
Registered: February 2004
Location: Hillsboro, Oregon
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| Mr ERFisher wrote on Wed, 18 July 2012 08:51 |
... Why not run the high volume pump all the time so this will never happen and it is all automatic. ?
Every new vehicle in the world does this.
|
Every new vehicle has fuel injection and NO mechanical pump.
I have had an engine fire (non-GMC) that a sticky float and a electric fuel pump were major contributors. I also would not run an electric pump through a mechanical pump full time due to the SLIGHT possibility of fuel leakage into the crank case.
Just my thoughts...
Mike Miller -- Hillsboro, OR -- on the Black list
(#2)`78 23' Birchaven Rear Bath -- (#3)`77 23' Birchaven Side Bath
More Sidekicks than GMC's and a late model Malibu called 'Boo'
http://m000035.blogspot.com
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| Re: [GMCnet] GMCer stuck [message #177231 is a reply to message #177141] |
Wed, 18 July 2012 19:43 |
Tim Conway
Messages: 412
Registered: September 2005
Location: Long Island, New York
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On Jul 18, 2012, at 11:44 AM, Mark wrote:
> My money's on it being a vapor lock issue. If so, it probably will go away if he only drives it when it's cooler, and stays away from stop and go traffic. I can't think of a worse case scenario than getting vapor lock on one of the NYC bridges in rush hour on a really hot day.
Nightmare scenario! I was happy to see an email at 12:47 last night/this morning saying he let it cool down for a few hours under an overpass and added five gallons of gas. Cranked it up and he got to his day's interim destination and rest at a Walmart's. I then saw an email 7:20 this morning, he was intending to meet an ex GMCer and then on to Vt or was it NH, maybe a Nor' Easters rally?
The heat's been pretty brutal here with very high humidity. Had some heavy rains a little while ago and that will lower temps for the next week. Rich is heading north so I think he'll be fine. And now he has a line on the issue, too.
He was a trouper through it all and was very impressed with the rapid response from the GMCnet. "It's been a long 24 hours but it's good to know there are so many good people out there."
Thanks Ken, Mark, Bill, Larry, Patrick and all.
Tim Conway
LI NY 78 PB
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| Re: [GMCnet] GMCer stuck [message #177338 is a reply to message #177231] |
Thu, 19 July 2012 20:46 |
Tim Conway
Messages: 412
Registered: September 2005
Location: Long Island, New York
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On Jul 18, 2012, at 8:43 PM, Tim Conway wrote:
> I then saw an email 7:20 this morning, he was intending to meet an ex GMCer and then on to Vt or was it NH, maybe a Nor' Easters rally?
>
> The heat's been pretty brutal here with very high humidity. Had some heavy rains a little while ago and that will lower temps for the next week. Rich is heading north so I think he'll be fine. And now he has a line on the issue, too.
To update, Rich emailed me today that he made it to the rally and is happily parked in the middle of 20 GMCs, finally able to relax. He is planning to address the vapor lock problem. I emailed a pdf file of relevant posts that I had saved over a few years but not updated in a few. In a search on the forum I found lots of threads starting with the most recent and updated my file.
Hope the other thread, Broke Down has a similar positive resolution...
Tim Conway
LI NY 78 PB
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| Re: [GMCnet] GMCer stuck [message #177343 is a reply to message #176959] |
Thu, 19 July 2012 21:23 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| ljdavick wrote on Mon, 16 July 2012 17:42 |
That's a good place to rest and check things out.
If it's spark, and the distributor is still turning, then the easy suspects are module or coil.
I'd trade my day at work to be on the road in a broken-down GMC!
Larry Davick
Fremont, California
A Mystery Machine
'76 (ish) Palm Beach
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I might just add that if the module or coil is not telling the fuel injection that there is spark, there will be no fuel delivery. In other words, during certain conditions, no spark can fool you into thinking the EFI is not injecting fuel.
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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| Re: [GMCnet] GMCer stuck [message #177344 is a reply to message #177338] |
Thu, 19 July 2012 21:30 |
George Beckman
Messages: 1085
Registered: October 2008
Location: Colfax, CA
Karma: 11
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| Tim Conway wrote on Thu, 19 July 2012 18:46 |
On Jul 18, 2012, at 8:43 PM, Tim Conway wrote:
> I then saw an email 7:20 this morning, he was intending to meet an ex GMCer and then on to Vt or was it NH, maybe a Nor' Easters rally?
>
>
To update, Rich emailed me today that he made it to the rally and is happily parked in the middle of 20 GMCs, finally able to relax. He is planning to address the vapor lock problem.
Tim Conway
LI NY 78 PB
|
Time,
Thanks for forwarding all the information. You might tell him that if the fuel injection vapor-locked, it is most likely on the suction side. Most EFI run 13 lbs pressure and up, keeping the fuel pressurized like the radiator cap does coolant. Unfortunately, on all our coaches, the low (suction) side does just the opposite. Less pressure means boiling at a lower temperature.
Need to make sure the tank is venting through the canister via the little separator valve by the front, left bogie. This vents two ways, in and out. If that little ball gets stuck, it could create a vacuum in the tanks making the suction problem even greater.
(Remember, taking the hose off the canister is not a good idea. 1) Fuel can belch into the engine compartment and 2) you could suck dirt in the line when things are cooling off.)
'74 Eleganza, SE, Howell + EBL
Best Wishes,
George
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