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G.M.C Safari will not stay running 4.3 v6


daveplace89's Avatar
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10-20-04, 08:55 PM   #1  
daveplace89
G.M.C Safari will not stay running 4.3 v6

I have a 1985 g.m.c safari with a 4.3 v6 engine, truck starts and idles for 3 to 4 minutes then shuts off , but after pumping gas it starts again , will drive for 500 to 600 feet and stalls , if i step on gas it dies , would this be fuel pump, gas tank is 1/2 full checked filter it is ok. check for blocked line it is ok no leaks in line or vac leaks found, fuel pump is on side of block not in gas tank any help would be appreciated thanks

 
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10-20-04, 10:48 PM   #2  
SimK68
Posted By: daveplace89 I have a 1985 g.m.c safari with a 4.3 v6 engine, truck starts and idles for 3 to 4 minutes then shuts off , but after pumping gas it starts again , will drive for 500 to 600 feet and stalls , if i step on gas it dies , would this be fuel pump, gas tank is 1/2 full checked filter it is ok. check for blocked line it is ok no leaks in line or vac leaks found, fuel pump is on side of block not in gas tank any help would be appreciated thanks

Ok, is this carburator or fuel injection? If its carburator, its more than likely a bad float or needle-valve, which regulates the amount of gas flow. If thats the case, I recomend replacing the carb.,and that can be pretty pricey, unless you know somone that can rebuild them, because rebuilding kits are only around $20.

Now if its fuel injection, that is over my simple mind (wait till more pros here reply), it could be a bad sensor.


Last edited by SimK68; 10-20-04 at 11:17 PM.
 
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10-21-04, 02:56 AM   #3  
it could be a fuel pump going bad or a carb problem more than likely a fuel pump if it runs for several minutes ok before it starts to act up.

 
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10-21-04, 04:50 AM   #4  
checking a mechanical fuel pump...

...requires doing the same tests as a fuel injected one...sort of. you must have fuel pressure AND volume. you can buy a pressure guage pretty economically for that since it requires no special hookup. disconnect the line going into the carb (BTW...this is where the fuel filter is...has it been changed?) connect the pressure guage to the line and start the engine and let idle (it'll run on what's left in the bowl) you should have 5 or 6 lb's of pressure. next, remove the guage and connect a suitable piece (old fuel line or whatever) of hose to the line and put the other end in a container...start the engine and let run for 30 seconds...the rule of thumb is you should get at least a pint in 30 seconds. if both of these tests are ok...it's not the fuel pump.

be sure to check the fuel line going from the tank to the pump very carefully...there are a few places where it is rubber and they always go bad with time...if the pump is pulling air in along the way...it won't pump much fuel.

i had fuel supply troubles with my motorhome and it was the rubber line at the very top of the tank where the steel line connects to the sending unit...it was pulling in air and it would starve especially when the weather was hot...replacing all of the hoses in the line cured my driveability problem completely.

 
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10-21-04, 05:14 AM   #5  
SimK68
Usually if its a machanical fuel pump that goes out, it leaks fuel on the side through the 'weap' hole indicating that the diaphram is out as well.

 
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10-21-04, 10:11 AM   #6  
daveplace89
the carb is only 4 years old as i had it changed when i had rebuild engine installed , it you keep putting gas in carb it will stay running, it is a mech pump in it check lines no leaks, will get new fuel pump and see if it works out
thanks

 
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11-02-04, 03:40 PM   #7  
hlangston
G.M.C Safari will not stay running 4.3 v6

Just reading through some of the posted threads when I saw yours.
Don't know if you've solve the problem yet. But what I'm about to
tell you I saw by accident once with one of my niece's van, a Pontiac Montana van. This may have nothing to do with yours, but her symptons were very simular. The van would start and run about a minute to two minutes and then shut down. As it turns out she had gotten a replacement key made without the appropriate computer code chip in it. The van would
run until the computer recognized that the key was not appropriate and
then shut down. I just happened to be in the vicinity to witness this
ordeal.

 
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11-03-04, 04:00 AM   #8  
this 1985 van...

...probably didn't have theft deterrent available way back then...not to mention that it restarts right away after pumping the accelerator. this is obviously a fuel problem. it would be nice if the original poster would post back and give us an update tho...

 
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11-03-04, 08:57 PM   #9  
daveplace89
Hello replaced fuel pump and cleaned carb and replace fuel plunger gaskets seat and needle in carb no luck still will not stay running sounds like it is getting to much air in carburetor reset float level . may have to get rebuilt carburetor do not no what to try next .

 
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11-04-04, 02:23 PM   #10  
What do you mean it sounds like it's getting to much air in the carb?Did you check the fuel pump as carguyinva suggested before buying one?Try getting a vacuum guage and attach it to the hose coming from the tank(inlet side)start the van and run it at about 1500 rpm for 15 seconds.You should have at least 15 inches of vacuum on the guage and it should hold for at least 1 minute.If it doesn't hold or doesn't get to 15 you have a leak in the supply line somewhere.

 
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