Very hard cold starts/ Runs great once it starts


Old 01-25-08, 06:30 PM
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Very hard cold starts/ Runs great once it starts

97 GMC Jimmy 4.3 4x4 135,000

First start of the day is terrible it just cranks and cranks. It tries to start then doesn't. It usually fires up with in 4-5 times turning the key. It's been cold here in michigan but there is obviously something wrong. I had a misfire code. So I tuned it up. (Plugs , Wires, cap, & rotor) I' ve put about 200 miles on since tune-up with no check engine light and it is running great. Once I get it started it will start right back up.
I can even drive somewhere and park for an hour or 2 come out and it will fire right up. I'm pretty sure it is fuel issue the other day it didn't want to start so I sprayed a little starting fluid in the throttle body and fired right up. Any help would be great.

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Old 01-26-08, 08:31 AM
Join Date: Dec 2007
Posts: 31
Your symptoms do sound fuel related to me and I have two ideas.

The first possibility is the fuel system has a check valve in it whose purpose is to maintain fuel pressure in the fuel lines after the engine is shut down. If this check valve is failing then fuel pressure may be leaking off and then it takes awhile for the fuel pump to build up pressure again. When you suspect you are going to have a hard time starting the engine try cycling the key 5 or 6 times without cranking the engine and then try starting it. When you cycle the key the fuel pump runs for a couple of seconds and this would build the pressure back up in the lines.

The second is a leaking fuel injector. I do not know if your engine is port fuel injection or throttle body. A leaking throttle body type injector could cause these same symptoms. Port fuel injection would be less likely to cause these symptoms. In either case if you suspect this try adding a bottle of Chevron with Techron to the gas tank. This works best if added right before taking a long trip. It is available at any parts store and is recognized in the auto repair industry as one of the best injector cleaning additives.

As for the check valve I do not know where it is located, many times it is right at the fuel pump.
Old 01-26-08, 10:37 AM
Join Date: May 2001
Posts: 516
You mention a hard start condition and you mention a tune up yet you do not mention changing the fuel filter. If you sprayed starting fluid into the throttle body and it started it must be fuel related and a fuel delivery problem.
Start with the basics, like a fuel filter. If that does't solve the problem you should check to see what the fuel pressure is and go from there.
Old 01-26-08, 11:47 AM
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Thanks for your thoughts. The fuel filter is rather new. I have CSEFI. I will definetely try these ideas out. Any more suggestions?

Thanks Dan
Old 01-26-08, 01:34 PM
Join Date: Feb 2005
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Low fuel pressure will cause a hard start. Your vehicle requires a certain amount of fuel pressure to start. It will run at a lower pressure, but needs that high pressure just to start. If you cycle the ignition on and off in 2 second intervals before you actually attempt to start it (next time it acts up) and it does start right up, replace the fuel pump (and pulsator if applicable). If you do have a fuel pressure gage, you should test the pressure next time it does act up just to verify.
Old 01-29-08, 02:40 PM
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Unfortanetly it seems to start alot easier when I cycle the fuel pump 4 or 5 times before I start it. I changed the fuel pump about 2 and a half years ago at around 100k. That $300 pump should last longer than that. I'm going to try and borrow fuel pressure gauge.

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