| Trip to Kansas and carb? problems [message #95482] |
Thu, 12 August 2010 10:00  |
docsdad
Messages: 32
Registered: May 2008
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Took trip from Thomson, Georgia to Pittsburg, Kansas this past week. Have made it back to my son's house in Murphysboro, Illinois. During trip, experienced following conditions. Early morning temps in high 70's with noon time temps in high 90's with some 100 days. MH is a 75 455 carb engine with 138000 miles. The engine appears to be a early replacement by GM dealer with first owner.. In early morning, runs great can travel 65 and 70 if necessary, Normal running speed 60 MPH. As temperature of day increases and about 2 or 3 hours of driving time, it starts to experience missing and faltering when going up hills and slight rises. With the cruise on it would be at full throttle and it would sputter and almost die. Also in town after it starts acting up, I experience same faltering when accelerating from a stop. Removing the cruise control, and using judicious minimum amount of throttle, it kept running but would slow significantly going up hills. Into low 40's and in Tennessee going up Mt Eagle, down to 20MPh. Never quit but put some additional gray hair on an old man.
I need some good advice on where to look. I have changed filters out to kazoo, replaced the ignition module twice, have a new coil to install, but think the problem is with the carb. Do not have the blocking plates in. If I can not get the carb to work, if that is the problem, then I think I will get a new aluminum manifold and fuel injection. I hate to go to this expense, however if it is not just the carb. I have rebuilt carb and for short trips under 2 hours, the unit runs like a dream. Note I was also towing a Tracker this time, but even when I was not towing, had the wife drive the towd, but when it was hot, it still experienced these same problems. Used only premium gas or no alcohol regular when I could find it. Last time I changed the ignition module, I put in new plugs, gap set to .045. The old plugs were way over .060. So put your heads together and give me some ideas. I am a shade tree mechanic and retired engineer so I think I can fix any thing, but not having a lot of luck with this problem. Also I have an electric fuel pump on this unit feeding into a large filter and it does not seem to help. It almost seemed to add to the problem when I would turn on and so I quit using it. Filters I took off showed a small amount of rust particles, but none were clogged and like I said above, when cool the next morning, It ran fine. I was limited to driving about 4 hours a day which does not make for good travel planning. Any thoughts will be appreciated. I am leaving the MH in Illinois so I can come to GMCMI convention in September but plan to work on it between now and then and if its not fixed the maybe you guys can solve my problem. PS I have never heard my fan run like everyone talks about so this week installed a new fan clutch and have heard it run only a few times never heard the old one run.
Jim Thompson 75 Avion GA
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