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hisandhers · 12-28-2014, 05:38 PM

We recently purchased a 1985 GMC Coachman motorhome with a 454 motor, 24 foot. We have to start it several times before it will continue running. It will start and immediately stall. The gas is good, as it had barely any when we bought it so our first stop was a gas station. Does anybody have any ideas as to why it does this? Thank you for your help.

wilson612000 · 12-28-2014, 06:23 PM

with the age gas pump or the filter in the tank so have someone check gas pressure and flow. how is the power if it pull ok on long pull forget my ideas

BFlinn181 · 12-28-2014, 06:39 PM

Couple of things to check, make sure the automatic choke is operating properly. Then I'd treat it to a new fuel filter. You could also do a volume test to see if the fuel pump is putting out the proper amount of fuel. There are lots of reasons it might start and stall, most having to do with fuel supply. I'd also put a can of carb cleaner in the fuel tank to help clean out any crud from sitting for long periods of time.

There are many forums on GMC 454 engines, do a search on Google for other tips about your starting problem.

Grandpere · 12-28-2014, 06:43 PM

I had the same problem with our 454. I did some adjusting on the quadrajet choke and that cured the problem. It was not setting up and staying engaged as it should when cold. It worked fine last year, but this year I had problems so it will change over time, even though one would not think so.

hisandhers · 12-29-2014, 07:17 PM

We have pretty much narrowed it down to the fuel pump. When we took the carb off, no fuel leaked out of the line. Thank you all who responded to my post.

BFlinn181 · 12-29-2014, 07:27 PM

Quote:

Originally Posted by hisandhers

We have pretty much narrowed it down to the fuel pump. When we took the carb off, no fuel leaked out of the line. Thank you all who responded to my post.

If you crank it, measuring how much fuel it pumps in 30 seconds (caught in a container) can tell you the health of the fuel pump.

OldToolmaker · 12-29-2014, 07:40 PM

The quadrajet does tend to drain back if it can. Don't use a fuel filter with a check valve, the alcohol in the gasoline makes the check valve body swell and do bad things to the fuel flow into the carb DAMHIK.

That being said, how long has it been since you lived with a carbureted engine?

Cool rig!

blousteau · 12-29-2014, 08:16 PM

We had a 83 Pace Arrow until 2006. 2 to 3 pumps on the pedal, pedal to the floor while cranking then let off when started. Always worked on ours. Rinse and repeat if not successful the first time, but not to many times or you will be flooded.

OldToolmaker · 12-30-2014, 11:03 AM

Well, I live in my '86 Rockwood full time. I bought it as a derelict so I've cleaned the carb, replaced the ignition coil and stuff like that to take care of the ravages of sitting.

You've had the fuel line off but did you watch the choke? Does it snap shut when cold? Does it open normally once the engine is running? Does the choke pull-off open the choke enough to keep the engine running?

I can point you in the right direction with some more information. That said if you just want to pull the carb and have it cleaned, I used this guy after I bought kits from two other vendors.

http://cliffshighperformance.com/

He has the information and the parts you need.

hisandhers · 01-04-2015, 03:30 PM

We want to thank everyone for their help!! We managed to fix the problem and it didn't cost us a penny. We decided to put the carb back on and made sure it was properly tightened (it was loose when we took it off). It started right up, no problem. Spent a few hours just hanging out at the RV and started it several times. Never a problem. Again, thank you to all!! Happy New Year!