High fuel pressure with supra pump

[Jbgrand]

I installed this Supra pump along with the Racetronix internal tank wiring kit. All components from the hoses to the tank were installed back in the original locations. Everything worked fine for about a week. During that time I had 55 lbs psi static pressure. I have an adjustable fuel pressure regulator from Bosch, which I had to turn down to get the 55 pounds.

All has been working well until recently. I tested the fuel pressure this morning and have 90 lbs psi while at idle. I turned the regulator down and it didn’t drop the pressure at all. My instinct tells me perhaps the fuel pump itself is setting too deep in the tank, but I’m not sure; since it worked fine at 55lbs at idle a week ago. I am looking for advice from others with a similar problem as this. All advice is appreciated.

Equipment: Running 87 T-Type: stock injectors, chip, and 160 degree thermostat. Bosch adjustable fuel pressure reg. Supra fuel pump.

 

[Scooter3800]

Make sure you don't have a restriction in the return line.

 

[salvageV6]

It sounds like a restricted return line take it off and blow some shop air through it to make sure it's clear.

One place they get gummed up is under the power steering pump area where the rubber line goes to metal at that funky GM fitting.

 

[BIGPSI]

x2 on the return line. put my 340 in years ago and the return was pinched. that thing hit like 110 psi at idle, car rumped and spewed black smoke.

 

[pacecarta]

if the return line works out to be good try a new gauge and take the schrader valve out of the fuel rail

 

[Jbgrand]

Thank You fellow members

I will try this Friday afternoon after work, and then post the results from there.
Have a great day
JBGrand

 

[Chuck Leeper]

I guess I'm a bit confused:
Why 55psi w/ a stock engine/injectors, etc?
What does the "pump setting too low in the tank", do?

 

[Clark6]

I guess I'm a bit confused:
Why 55psi w/ a stock engine/injectors, etc?
What does the "pump setting too low in the tank", do?

I think he's refering to " sitting too low" as in bottoming out blocking suction,
but if he put the braced filter on it that came with the pump shouldnt be a problem. but if he put the flat unbraced filter on & its bottoming out then yes, i could see a problem.


Yes i see your point also Chuck, 55psi at idle is very high. I think he needs to turn it down somemore also when the other things are straightened out.

 

[Chuck Leeper]

Setting/sitting..

I think he's refering to " sitting too low" as in bottoming out blocking suction,
but if he put the braced filter on it that came with the pump shouldnt be a problem. but if he put the flat unbraced filter on & its bottoming out then yes, i could see a problem.


Yes i see your point also Chuck, 55psi at idle is very high. I think he needs to turn it down somemore also when the other things are straightened out.

If the pump setting, [or sitting], on the bottom of the tank, is not going to create a problem w/ high fuel psi, and the inability to set the regulator. BeingoOn the bottom will/can cause cavitation, low psi, flow issues, and/or noise from the pump.

"I tested the fuel pressure this morning and have 90 lbs psi while at idle. I turned the regulator down and it didn’t drop the pressure at all."
As others have mentioned: Return line and/or fpr problems. That's where I'd start.
I'd also look at the tank vent.

 

[challengermike]

I had high fuel pressure when i installed my denso but it wasnt that high,i think it was 50 psi line off.After driving it like that for about 3,000 miles i was able to turn it down.I never did find out why it was high,i was just guessing that the pump put out more than it was suppost to.

 

[Jbgrand]

problem solved !

Thanks to everyone for your advice.
Turns out both the supply and return lines were bent when installed by the previous owner. Both lines were twisted in the straight run that lies between the block and alternator /Belt Tensioner bracket. Unless you are looking really hard, you won’t see these lines are bent in this area;so it’s an area to look for.
Now I am busy getting the car used to all that extra fuel and air. Thanks again.