I have an 87 IROC with a TPI 305. I just replaced the fuel pump about 2 months ago and this afternoon it starting making strange almost moaning like sounds while the car is running. Its like it never stops priming. The car runs ok, a little rough at idle but its always ran that way. When I take the gas cap off its under extreme pressure, especially with the car running. is this normal? Any ideas on whats causing this? I also noticed the oil pressure gauge isnt running where it normally does, could these be related? Any ideas would be appreciated!

 

Check your fuel pressure at your schrader valve, then I will suspect what I suspect I will be supsecting when i do suspect.

 

The fuel pressure when the pump primes get to 42lbs then instantly drops to 0. The engine does start and the pressure peaks at about 38lbs at idle, the needle bounces between 36 and 38. Any ideas? Is it normal for the pressure to drop to "0" after priming?

 

Have you ever replaced that vent valve down by the left rear tire?

 

No i haven't. I just got back in from doing some trouble shooting and when I let the pump prime and then pinch the return line the pressure holds. Chilton's says this is a bad pressure regulator, is there anything else that may cause this?

 

Do you by any chance have an adjustable fuel pressure regulator on your car, maybe one made by Holley?

 

No, it is the stock unit.

 

Okay here a couple of items that could cause your problem besides the fuel pressure regulator.

leaky injectors (ruled out by pinching return line)

pulsator coupling on fuel pump leaking or falling off.

restricted fuel line/clogged fuel filter (did you change the filter when you changed the pump?)

fuel pump check valve not holding.

I have a troubleshooting chart for this, if you would like a copy I can post it.

 

What's it sound like when the tank is full?

 

I did change the filter when I put the pump in. I checked the pulse dampener right before I put the pump assembly back in the tank and it all seemed tight. I'd really hate to have to take that tank out again. I removed and cleaned the injectors about 3 months ago and replaced the o-rings, no evidence of a leak on any of them. I pinched the fuel pressure line after primimg the pump and the pressure still dropped instantly, but pinching the return line after priming kept the pressure at the valve. any troubleshooting guide you have would be appreciated.

 

Red Devil, the thing sounds like a humpback whale, no kidding. It sounds like the pump is running to try to keep up.

 

It's in the e-mail. I know this is a dumb question, but have you checked to see if you may have accidently put the fuel filter on backwards? It has been known to happen and does quite often if you don't pay attention to what you're doing. Just a thought!!!!!!!!!!!!

 

Lol...yep the filter is on right. Been driven daily for the last 2 months, started acting up Friday.