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GMC Jimmy fuel pressure issues
12-04-2011, 11:20 PM
Post: #1
GMC Jimmy fuel pressure issues


I have a 97 jimmy. It was starving for gas so I replaced the fuel pump yesterday. It still is hard to start. I had it at a dealer last winter and they told me the fuel pressure was bleeding off somewhere. They had taken the intake apart but could not find a problem there. It does not give off the smell of a vehicle flooding with gas, no black smoke, mileage is ok, no puddles. I have to use starting fluid to get it to start. I have replaced the fuel filter too. I'm wondering if the regulator is bad? Anyone have any ideas?
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12-05-2011, 07:02 PM
Post: #2
RE: GMC Jimmy fuel pressure issues
(12-04-2011 11:20 PM)jimmydriver Wrote:  

I have a 97 jimmy. It was starving for gas so I replaced the fuel pump yesterday. It still is hard to start. I had it at a dealer last winter and they told me the fuel pressure was bleeding off somewhere. They had taken the intake apart but could not find a problem there. It does not give off the smell of a vehicle flooding with gas, no black smoke, mileage is ok, no puddles. I have to use starting fluid to get it to start. I have replaced the fuel filter too. I'm wondering if the regulator is bad? Anyone have any ideas?

have you tried replacing the fuel filter because with a dirty fuel filter or plugged filter it will restrict gas from geting to the motor... besides they are real cheap somewhere around 10 dollars
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12-10-2011, 01:06 AM
Post: #3
RE: GMC Jimmy fuel pressure issues
yep it has a new filter. I still haven't checked the fuel pressure.
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12-10-2011, 06:56 AM
Post: #4
RE: GMC Jimmy fuel pressure issues
I think that checking the fuel pressure would be the first thing to do. You could be working on a "Fuel" issue only to find that the temperature sensor isn't working. Another thing to try would be to have it checked with a "High End Scanner." Check for codes, record all code NUMBERS, post those NUMBERS here for review, & have the codes cleared. While the scanner is hooked up you can bring up sensor readings. This would be best with the engine cold at a time when you would have to use starting fluid. Check the temperature sensor reading, MAF, MAP, etc..

Also, what Engine? Transmission? Mileage?

Please let us know what you find.

Thanks for using the forum,
Garner

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12-10-2011, 02:15 PM (This post was last modified: 12-10-2011 02:43 PM by Rupe.)
Post: #5
RE: GMC Jimmy fuel pressure issues
95% of these were 4.3 V-6 engines so let me throw my 2 cents into the ring.

Yes, do check for codes and clear them so anything new will be curent and likely help point to an issue. I would also lean very strongly toward checking the fuel pressure because even being 10 psi low will cause hard starting. Should be 55 - 60 psi and hold for many hours. The only place the fuel can go if it's not leaking externally is back into the tank or into the engine.

*IF* the pressure regulator is leaking externally there will be a smell of fuel at the intake boot. If the fuel is leaking elsewhere (dripping injector?) there may be no obvious clues other than gradual diluting of the oil. The regulator can also "leak by" meaning it's leaking back to the tank, but this is rare in my opinion. More likely the replacement pump assembly is not up to snuff. (off brand unit?)

Let us know how you make out.
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12-10-2011, 07:03 PM
Post: #6
RE: GMC Jimmy fuel pressure issues
Forgot to mention that the pressure regulator is part of the injector body, which is located under the intake manifold, so it would be a wise move to have a good diagnosis just to avoid extra work here.

Another item to check is the amp draw of the fuel pump. IOW, if it is straining / binding for some reason the draw will be high. Look for something around 5 amps. If it's near 10 amps or more then that would point to a possible intermittent issue and a low pressure reading will confirm it as a pump problem rather than somewhere else.
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12-11-2011, 03:06 AM
Post: #7
RE: GMC Jimmy fuel pressure issues
Does it have a throttle body or the plastic intake. I've come across similar problem with a 99 blazer and it was inside the intake. It has one big injector with six plastic hoses to deliver fuel to each cylinder. They are prone to have problems. goodluck
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