Home » Public Forums » GMCnet » Engine start problem
| Engine start problem [message #299848] |
Fri, 29 April 2016 08:39  |
JohnS
Messages: 126
Registered: December 2014
Location: Vacaville, CA
Karma: -2
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Senior Member |
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We have been out in the Stretch for over a week now and all has been going well except for one annoying problem. When the engine is cold (well cool... this IS in Southern Calif!) & the Outside Air Temperature is below about 50F, no problem. If we get a later start & the OAT gets to 60-70, it seems like the battery will run down before it starts. Hot starts later in the day after a lunch or fuel stop are almost instantaneous.
My procedure for a cold start is; electric pump on, depress accelerator half way to set the choke, & I am rewarded with a very quick start. That does not work when it is warm, so have also tried not running the pump, not setting the choke, and the combination of those two... still no go.
This is a fresh (4000 mile) 455. When it was installed, we also put in an aluminum intake, new Patterson Quadrajet, Distributor, & Plug Wires. The Plugs are new NGK 6BKR6EI. There is no mechanical pump, have a Carter 4070 on each tank.
We did not use the coach last spring and summer due to our medical problems so this trouble is new to my experience with this motorhome. Have not had the engine cover up to look during one of these episodes, the pressure to get going makes us start off, just glad to finally have it running!
Any ideas or suggestions will be much appreciated.
John Shutzbaugh, Vacaville, CA, ncserv@aol.com;
78 Buskirk stretch, "What were we thinking?"
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| Re: Engine start problem [message #299862 is a reply to message #299848] |
Fri, 29 April 2016 11:05  |
g.winger
Messages: 792
Registered: February 2008
Location: Warrenton,Missouri
Karma: 0
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Senior Member |
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When having hard start problems due to slow cranking,,, you need to do a "Loaded Voltage Drop Test". With the engine warm and the ignition disabled hook up a good voltage meter (set to volts DC of course). One leed on the negative battery POST (not clamp) and the other to the engine block. Crank. whats the reading. If its several volts thats the drop while cranking. Bad ground. repeat for the positive cable,,,, POST and at the starter. Notice I typed POST. IF you have a bad connection between the clamp and the Battery the test will not be accurate. DON"T USE OHMS TO TEST A BATTERY CABLE. One strand of copper will give you "zero" ohms but will not carry 200 amps!!!! This is a looded voltage test. Search Utube,,,,, and watch some of Paul Danners vids on this test (aka scannerdanner) This guys vids will halp you,,,, GL PL
Paul Leavitt
78 Rear
Bath Roayale, 500 cad
Hubler, galvanized frame and still no dash!!
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| Re: Engine start problem [message #299865 is a reply to message #299848] |
Fri, 29 April 2016 11:38 |
Bullitthead
Messages: 1411
Registered: November 2013
Karma: 5
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Senior Member |
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Try holding the throttle WIDE OPEN with just one push and then crank to see if it needs AIR instead of fuel on that starting condition. I have the same problem with mine after a short trip from a cold engine. The fuel is boiling in the carb on mine due to the stock manifold, but you may have the drill-bore leak common to rebuilt Quadrajets. If manipulating fuel/air makes no difference, then I would look at the power supply for the ignition system as Paul posted.
Terry Kelpien
ASE Master Technician
73 Glacier 260
Smithfield, Va.
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| Re: [GMCnet] Engine start problem [message #299882 is a reply to message #299848] |
Fri, 29 April 2016 14:53 |
k2gkk
Messages: 4452
Registered: November 2009
Karma: -8
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Senior Member |
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I believe that in general, you set the accelerator slowly all the way to set a choke!
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
~~ ~ D C "Mac" Macdonald ~ ~~
~ ~ Amateur Radio - K2GKK ~ ~
~ ~ Since 30 November '53 ~ ~
~ ~ USAF and FAA, Retired ~ ~
~ Member GMCMI and Classics ~
~ ~ ~ Oklahoma City, OK ~ ~ ~
~~ ~ ~ "The Money Pit" ~ ~ ~~
~ ~ ~ ~ TZE166V101966 ~ ~ ~ ~
~ ~ ~ '76 ex-Palm Beach ~ ~ ~
~~ k2gkk + hotmail dot com ~~
~ www.gmcmhphotos.com/okclb ~
~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~
______________
|[ ]~~~[][ ][]\
"--OO--[]---O-"
> Date: Fri, 29 Apr 2016 07:39:49 -0600
> To: gmclist@list.gmcnet.org
> From: ncserv111@gmail.com
> Subject: [GMCnet] Engine start problem
>
> We have been out in the Stretch for over a week now and all has been going well except for one annoying problem. When the engine is cold (well
> cool... this IS in Southern Calif!) & the Outside Air Temperature is below about 50F, no problem. If we get a later start & the OAT gets to 60-70, it
> seems like the battery will run down before it starts. Hot starts later in the day after a lunch or fuel stop are almost instantaneous.
>
> My procedure for a cold start is; electric pump on, depress accelerator half way to set the choke, & I am rewarded with a very quick start. That does
> not work when it is warm, so have also tried not running the pump, not setting the choke, and the combination of those two... still no go.
>
> This is a fresh (4000 mile) 455. When it was installed, we also put in an aluminum intake, new Patterson Quadrajet, Distributor, & Plug Wires. The
> Plugs are new NGK 6BKR6EI. There is no mechanical pump, have a Carter 4070 on each tank.
>
> We did not use the coach last spring and summer due to our medical problems so this trouble is new to my experience with this motorhome. Have not had
> the engine cover up to look during one of these episodes, the pressure to get going makes us start off, just glad to finally have it running!
>
> Any ideas or suggestions will be much appreciated.
> --
> John Shutzbaugh, Vacaville, CA;
> 77 Eleganza, bought it new, can't blame PO, and
> 78 Buskirk stretch, "What were we thinking?"
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| Re: Engine start problem [message #299919 is a reply to message #299848] |
Sat, 30 April 2016 07:33 |
JohnS
Messages: 126
Registered: December 2014
Location: Vacaville, CA
Karma: -2
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Senior Member |
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Thanks for the input, guys.
I don't really have a slow cranking problem, due mainly, I think, to incorporating Gene Fisher's suggestions on starter wiring. I ran a new 2-0 cable direct from my dual post battery to the (new) starter... it really spins over!
Have been at an RV park in Oceanside for a couple of days seeing sights and relatives using the towed. Sunday when we leave for Temecula, I'll get the engine cover up and see if I am really setting the choke with my technique. Then if the problem re-occurs, will try the Wide Open Throttle. This should not be that complicated! Thanks again.
John Shutzbaugh, Vacaville, CA, ncserv@aol.com;
78 Buskirk stretch, "What were we thinking?"
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| Re: Engine start problem [message #299920 is a reply to message #299848] |
Sat, 30 April 2016 07:38 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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JohnS wrote on Fri, 29 April 2016 09:39We have been out in the Stretch for over a week now and all has been going well except for one annoying problem. When the engine is cold (well cool... this IS in Southern Calif!) & the Outside Air Temperature is below about 50F, no problem. If we get a later start & the OAT gets to 60-70, it seems like the battery will run down before it starts. Hot starts later in the day after a lunch or fuel stop are almost instantaneous.
My procedure for a cold start is; electric pump on, depress accelerator half way to set the choke, & I am rewarded with a very quick start. That does not work when it is warm, so have also tried not running the pump, not setting the choke, and the combination of those two... still no go.
This is a fresh (4000 mile) 455. When it was installed, we also put in an aluminum intake, new Patterson Quadrajet, Distributor, & Plug Wires. The Plugs are new NGK 6BKR6EI. There is no mechanical pump, have a Carter 4070 on each tank.
We did not use the coach last spring and summer due to our medical problems so this trouble is new to my experience with this motorhome. Have not had the engine cover up to look during one of these episodes, the pressure to get going makes us start off, just glad to finally have it running!
Any ideas or suggestions will be much appreciated.
John,
This is most certainly aggravating.
There are several possibilities, and but for a 2000 mile air gap, we could probably sort it pretty fast. The simple view of the situation is that it is either rich or lean from fire point.
If you have to crank a good 455 more than three turns before it fires, something is wrong, shut down, regroup and try again.
First thing, open the hatch and the air filter and make sure the the choke is actually closing at your 60~70° start. If it isn't you can adjust it. It is an electric choke (now) so those are a little touchier to set. If you see it is not quite closed, try a two pump start. That just might do it. That was all about a lean start problem.
Second, a rich start can be every bit as bad. They are harder to deal with normally, but you have electric pumps. That makes this easy. Leave the fuel pumps off and crank. If it fires, turn the pump(s) back on right then. If it is rich, it may take several three turn cycles to clear out and fire.
Matt
Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
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| Re: [GMCnet] Engine start problem [message #299927 is a reply to message #299920] |
Sat, 30 April 2016 11:15 |
jimk
Messages: 6734
Registered: July 2006
Location: Belmont, CA
Karma: 9
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Senior Member |
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John,
Give me a all as we can do better
On Sat, Apr 30, 2016 at 5:38 AM, Matt Colie wrote:
> JohnS wrote on Fri, 29 April 2016 09:39
>> We have been out in the Stretch for over a week now and all has been
> going well except for one annoying problem. When the engine is cold (well
>> cool... this IS in Southern Calif!) & the Outside Air Temperature is
> below about 50F, no problem. If we get a later start & the OAT gets to
> 60-70,
>> it seems like the battery will run down before it starts. Hot starts
> later in the day after a lunch or fuel stop are almost instantaneous.
>>
>> My procedure for a cold start is; electric pump on, depress accelerator
> half way to set the choke, & I am rewarded with a very quick start. That
>> does not work when it is warm, so have also tried not running the pump,
> not setting the choke, and the combination of those two... still no go.
>>
>> This is a fresh (4000 mile) 455. When it was installed, we also put in
> an aluminum intake, new Patterson Quadrajet, Distributor, & Plug Wires.
>> The Plugs are new NGK 6BKR6EI. There is no mechanical pump, have a
> Carter 4070 on each tank.
>>
>> We did not use the coach last spring and summer due to our medical
> problems so this trouble is new to my experience with this motorhome. Have
> not
>> had the engine cover up to look during one of these episodes, the
> pressure to get going makes us start off, just glad to finally have it
> running!
>>
>> Any ideas or suggestions will be much appreciated.
>
> John,
>
> This is most certainly aggravating.
>
> There are several possibilities, and but for a 2000 mile air gap, we could
> probably sort it pretty fast. The simple view of the situation is that it
> is either rich or lean from fire point.
>
> If you have to crank a good 455 more than three turns before it fires,
> something is wrong, shut down, regroup and try again.
>
> First thing, open the hatch and the air filter and make sure the the choke
> is actually closing at your 60~70° start. If it isn't you can adjust it.
> It is an electric choke (now) so those are a little touchier to set. If
> you see it is not quite closed, try a two pump start. That just might do
> it.
> That was all about a lean start problem.
>
> Second, a rich start can be every bit as bad. They are harder to deal
> with normally, but you have electric pumps. That makes this easy. Leave
> the
> fuel pumps off and crank. If it fires, turn the pump(s) back on right
> then. If it is rich, it may take several three turn cycles to clear out and
> fire.
>
> Matt
>
> --
> Matt & Mary Colie - Members GMCMI, GMCGL, GMCES
> '73 Glacier 23 - Still Loving OE Rear Drum Brake with Applied Control Arms
> Now with both true Keyless and remote entry
> SE Michigan - Twixt A2 and Detroit
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
--
Jim Kanomata
Applied/GMC, Fremont,CA
jimk@appliedairfilters.com
http://www.appliedgmc.com
1-800-752-7502
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Jim Kanomata
Applied/GMC
jimk@appliedairfilters.com
www.appliedgmc.com
1-800-752-7502
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| Re: Engine start problem [message #299937 is a reply to message #299848] |
Sat, 30 April 2016 17:39 |
JohnL455
Messages: 4447
Registered: October 2006
Location: Woodstock, IL
Karma: 12
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Senior Member |
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Cold. Depress all the way once. Crank with foot off pedal. After a short time running kick down fast idle. Repeat until warm and at base idle.
Hot. Hold pedal about 1/4 way down and crank.
Flooded. Hold pedal firmly to floor without pumping and crank.
Paraphrasing GM owners manuals from the 70s.
The above depends on the choke, fast idle, and choke unloader settings being correct.
John Lebetski
Woodstock, IL
77 Eleganza II
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| Re: Engine start problem [message #300018 is a reply to message #299848] |
Mon, 02 May 2016 09:32 |
JohnS
Messages: 126
Registered: December 2014
Location: Vacaville, CA
Karma: -2
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Senior Member |
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After seeing the input from you gentlemen, I decided it was past time for me to do some basics. First off, I READ THE MANUAL to refresh myself on what happens and how it is accomplished in the choke system. Then at 0600 and an Outside Air Temperature of 52F I determined that my method of depressing the accelerator half way does set the choke and it closes all the way. I am pretty sure there is less fuel pumped into the primaries this way, but am unsure if that is good or bad. Then I "unset" the choke to wait for the day to warm up.
At departure time of 10 am and an OAT of 62F checked again & found the choke closed completely when set. Start was normal, so I guess this was still a "cool" morning! Will try again on a warmer day (now I'm keeping track of things) and report if any conclusions are reached.
Thanks again for all your knowledge and help, John Shutzbaugh
John Shutzbaugh, Vacaville, CA, ncserv@aol.com;
78 Buskirk stretch, "What were we thinking?"
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