intermittent start issue

intermittent start issue

Postby 4ntzilla [OP] » July 17th 2010, 2:36am

97 Astro 4.3L turns over but very hard to start, especially in the morning. After it does start it runs fine. No trouble codes. Fuel pressure 55psi. Replaced coil,cap,rotor,plugs, and wires. Have strong spark. Any ideas what would be the next logical step? Please help.
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Re: intermittent start issue

Postby LEVE » July 17th 2010, 2:54am

First determine if it's fuel or electrical. Try, in the morning when the engine is cold, spraying a little starting fluid in the air intake. If the engine takes right off and runs off the starting fluid then the problem is fuel related. If not, it's related to the fuel injection....
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Re: intermittent start issue

Postby 4ntzilla [OP] » July 17th 2010, 11:43am

Sprayed starting fluid, and it fired up immediately. Fuel pressure is normal, so I assume the fuel pump is good. Not sure what to replace next.
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Re: intermittent start issue

Postby LEVE » July 17th 2010, 2:19pm

so I assume the fuel pump is good. Not sure what to replace next.
Ok... that's a little presumptuous. What is your reasoning for ruling out the pump? You know know the electronics for the timing, cps/kps, ect. are good; that does narrow it down to fuel delivery.

The fuel pump could still be going south. What's the spec for your engine? Isn't it about 60-66psi? If so, then 55psi is too little pressure and the pump should be replaced.

Try the turning the ignition from off to RUN mode two or three time, holding the for no more than 2 seconds in RUN mode. Then go to START mode and see if the engine starts right up.

I'm still betting on the fuel pump.
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Re: intermittent start issue

Postby 4ntzilla [OP] » July 17th 2010, 2:36pm

Okay I tried that and it seemed to start a little faster than usual.With key on the fuel pressure is 58-59 psi. The problem is that within 5 minutes gauge drops to 40psi. Obviously I have a leak down issue. I guess I'll replace the fuel pump since it is not giving me 60-66psi. I just hope its not something under the upper intake leaking off my pressure. Thanks.
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Re: intermittent start issue

Postby rev_les » July 17th 2010, 2:45pm

4ntzilla wrote:Okay I tried that and it seemed to start a little faster than usual.With key on the fuel pressure is 58-59 psi. The problem is that within 5 minutes gauge drops to 40psi. Obviously I have a leak down issue. I guess I'll replace the fuel pump since it is not giving me 60-66psi. I just hope its not something under the upper intake leaking off my pressure. Thanks.

The fuel pressure regulator could be contributing,you shouldn't have that much leak down that fast. It is in fact, under the upper intake, but it's really not that bad of a job to replace it.
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Re: intermittent start issue

Postby 4ntzilla [OP] » July 17th 2010, 6:03pm

Hooked fuel pressure gauge in right before fuel filter(rigged up with a section of hose and some clamps) and fuel pressure still leaks down 10psi within 3 minutes. I now feel 90% certain that its the fuel pump. If anyone has any other ideas please let me know. Thanks
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Re: intermittent start issue

Postby LEVE » July 17th 2010, 6:11pm

If the residual fuel pressure bleeds off that fast... it's likely the problem. How I'd do the job is to replace the fuel pump first, it makes sense. After that's done, be prepared to buy and replace the regulator, if needed.
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