1996 Silverado fuel pressure update.

[stryped]

Well, I need your smarts as always to help me asses the situation. Right now my truck starts fine. I have driven it 5 miles twice with no problems. The only thing I did that could have solved the problem was drill out the cat in question. You know more than me on these things, but it just seems to me that a bad cat would not cause an intermittent starting and surging like it is running out of gas problem while driving. Checking the fuel pressure it is within spec. However it is not in spec with regards to holding pressure. Upon reading more about it this indicates: A) Leaking check valve in fuel pump or B) leaking regulator/injectors.

For lack of not having anything else I pinched the hoses with vice grips last night. However, they were not as tight as I probably should have doen them as I was afraid of damaging the hoses. Fuel pressure still dropped but it seemed to do it more slowly. I did another test, I punched only the return line and turned KOEO. Pressure shot up to about 80 psi. Am I understanding correctly that this indicates a bad fuel pressure regulator?

I noticed last night in the cold that it looks like there is white smoke coming out of the exhaust. It may have always been there. I don’t know.

I would like to get the fuel pressure drop repaired but I am still not convinced as to whether it is A or B. If this truck did not have so many miles, I would consider replacing the entire “spider”. Aparently there is an update to convert SCFI to MPI. (Apparently there were problems with the SCFI). I would also replace the fuel pump and sending unit. (My gas guage is jumping around). However using OEM parts you are looking at 600 bucks.

I am afraid to use Autozone parts (Airtek) in such critical areas.

I would consider leaving as is, but I have read that if the regulator is indeed leaking, it will dump gasoline in the crankcase and could potentially ruin the engine. I could replace just the regulator, but it may also be an injector that is not holding pressure. It does seem easier to just replace the “spider” although more costly.

I am just looking for advice. Left truck sitting outside overnight in the cold and it started up this morning. So I am puzzeled and a little afraid to drive it until I can get my head around it.

As always I appreciate it.

[ChevyTech77]

Well, I need your smarts as always to help me asses the situation. Right now my truck starts fine. I have driven it 5 miles twice with no problems. The only thing I did that could have solved the problem was drill out the cat in question. You know more than me on these things, but it just seems to me that a bad cat would not cause an intermittent starting and surging like it is running out of gas problem while driving. Checking the fuel pressure it is within spec. However it is not in spec with regards to holding pressure. Upon reading more about it this indicates: A) Leaking check valve in fuel pump or B) leaking regulator/injectors.

 

For lack of not having anything else I pinched the hoses with vice grips last night. However, they were not as tight as I probably should have doen them as I was afraid of damaging the hoses. Fuel pressure still dropped but it seemed to do it more slowly. I did another test, I punched only the return line and turned KOEO. Pressure shot up to about 80 psi. Am I understanding correctly that this indicates a bad fuel pressure regulator?

 

I noticed last night in the cold that it looks like there is white smoke coming out of the exhaust. It may have always been there. I don’t know.

 

I would like to get the fuel pressure drop repaired but I am still not convinced as to whether it is A or B. If this truck did not have so many miles, I would consider replacing the entire “spider”. Aparently there is an update to convert SCFI to MPI. (Apparently there were problems with the SCFI). I would also replace the fuel pump and sending unit. (My gas guage is jumping around). However using OEM parts you are looking at 600 bucks.

 

I am afraid to use Autozone parts (Airtek) in such critical areas.

 

I would consider leaving as is, but I have read that if the regulator is indeed leaking, it will dump gasoline in the crankcase and could potentially ruin the engine. I could replace just the regulator, but it may also be an injector that is not holding pressure. It does seem easier to just replace the “spider” although more costly.

 

I am just looking for advice. Left truck sitting outside overnight in the cold and it started up this morning. So I am puzzeled and a little afraid to drive it until I can get my head around it.

 

As always I appreciate it.

 

 

Needs an mfi kit. Pressure should spike with the return hose crimped off because where is the excess fuel pressure, that the regulator is trying to bleed off, going to go with the return side shut down? Spend the money for the mfi kit or drive it as is.

[txab]

Try not to start new threads on the same subject. Best to use one thread for your problem

[stryped]

So does this tell me the regulator is working? (It got up to 80 psi). Would you recomend the kit from autozone?

 

Can I screw an adapter into the fuel filter and read the pressure there? (With the engine side of the fuel line disconnected? If the pressure holds with KOEO I assume it has to be somethign on the upper end, right?