Fuel pump only 25 PSI

HI everyone,
I replaced the fuel pump on my SC with a Deatschwerks DW200. Ran it for 30 miles and the car didn't seem right. So I went and checked the fuel pressure and got 25 psi. I have a Accufab AFPR and tried to adjust it - nothing. No matter how much or which way I turned the Accufab still 25 PSI. I pinched the return line and still 25 PSI. Fuel filter is new. IS this a bad pump? I used the stock electrical lines in the tank and I know they are thin but could that cause this problem? Also when I turn the key the pump doesn't prime - no pressure.

Thanks, Ralph

What hose inside the gas tank are you using?

That special r35 or whatever it is - fuel hose. Super expensive submersible hose.

Take the pump out and bench test it.

I've had that hose partially pop off the pump after a new install. Might be half on half off..

sounds like the tank.pump needs to come out to check it

I know you said you pinched the return line but I think you should dead head the pump with a gauge before you do anything too drastic. If you still get the same reading with the gauge attached directly to your feed line then you can test your theory about the power wires with the tank half way dropped and big wires connected to a charger or good charged battery. If you think the lines are at fault, put the gauge right on the pump sender with a short piece of hose. I don't have any experience with the pump you have but with my walbro I can easily get way more pressure than I'll ever need.

Do those pumps have a built in relief valve? If so, it's possible that it's not working correctly.

The Deatschwerks DW200 pump is a good one. WAY quieter than a 255 Walbro pump & E-85 compatible too. All of mine will easily instantly peg a 100 PSI gauge when pinching off the return line. IIRC, they come with a 3 year no questions asked warranty. Anything can happen though, you might have just received a bad one. Yeah like others have said, take it out and bench test it. Not that big of a job, it could be a lot worse.
You may want to check voltage at the pump. I just looked at instructions for a DW300 pump and minimum input voltage is 6 volts (max of 18 volts). Seems suspicious that pump isn't priming when you turn on the key? Issue maybe with ASD relay? Why did you replace old pump? Were you having issues with the old pump? Many DW pump installation kits don't come with pigtail connector. Did yours come with one? The factory Walbro used separate -/+ spade connectors while the 255 Walbros came with a plastic connector that plugs into the pump. The Walbro and the DW pumps use the same connector. So if you didn't change the connector out, maybe someone previously did and maybe that might be worth looking at more closely.
Sorry for all the questions, just trying to help.
BTW is this my old SC? I sold black w/silver 87 SC to Derek O. in your area, many years ago. I think he sold it to Wayne in your home town.
Todd

Thanks guys. A little more backstory:

I had the stock 2 pump setup in the car a few months ago - no issues with it. Switched over to the Walbro since the stock pump was 30+ years old. It seemed to me rather strange that I had to run 57PSI pressure for the +20 injectors with the Walbro when I could run 45PSI on the stock 2 pump setup. The car would not run right unless I turned up the fuel pressure to 57 PSI. So I thought there may have been something wrong with the Walbro (not enough flow). I replaced the fuel filter twice. Installed the DW200 and it ran OK for 20 miles then the car fell flat on its face when accelerating. The O2 sensor seemed lazy to me so I put a new one in. Thats when I checked the fuel pressure on the DW200 and found out it was only 25PSI.

Yes I replaced the pigtail connector on teh DW200 as I couldnt get the Walbro connector to fit exactly right.

Todd: Nope this is my own car I have had since 1987. But yes I am familiar with Dereks/Waynes and now Aarons SC. :-)

Fuel pump creates fuel flow. Fuel pump flows more fuel at low fuel pressure than at high pressure.

Fuel pressure regulator creates restriction and fuel pressure. Some regulator are adjustable, most are not. They also have a vacuum reference port so they can match the fuel pressure with intake vacuum\pressure so the fuel pressure is always at a constant with intake vacuum\pressure.

Fuel injectors flows more at higher fuel pressure than low fuel pressure.

If your fuel pressure regulator is a 3.8 bar stock one, and you only see 25psi at the fuel rail and your gauge is working correctly, you either have a broken fuel pressure regulator, or somewhere inside the fuel system is bleeding off pressure, mostly likely at the fuel pump hanger.

Fuel pump on a returned system is an on/off part. I havn't come across any "weak" fuel pump myself. They either work, or they don't.

Quote:

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Originally Posted by tryingbe

If your fuel pressure regulator is a 3.8 bar stock one, and you only see 25psi at the fuel rail and your gauge is working correctly, you either have a broken fuel pressure regulator, or somewhere inside the fuel system is bleeding off pressure, mostly likely at the fuel pump hanger.

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Its Accufab AFPR. But when I pinched off the return line I still wasn't getting pressure, so I *think* the FPR is OK. Yeah I need to pull the pump out and see if it is leaking at the hanger.

UPDATE: The hose seemed loose on the fuel line inside the tank. Specifically were it connected to the metal line as it has no barb on the end of it. I think the clamp wasn't tightening down enough (EFI clamap) and fuel was leaking past it. I redid to hose and pressure seems much better now. Just need to dial in the fuel pressure again.

I'm running +20s with a stock logic module. Right now I am at 34PSI with vacuum line disconnected where it seemed to idle OK. Does that seem to be in the ballpark or should I up it to around 40?

No wideband?
No stock injectors?


Stock TII injectors is 33lbs at 55psi. Your current injectors is at 42lbs at 55psi, to bring your injectors down to 33lbs is 33psi fuel pressure.

http://www.deatschwerks.com/fuel-cal...ure-calculator

Excellent. Thanks!!

Quote:

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Originally Posted by DevoBuzz

UPDATE: The hose seemed loose on the fuel line inside the tank. Specifically were it connected to the metal line as it has no barb on the end of it. I think the clamp wasn't tightening down enough (EFI clamap) and fuel was leaking past it. I redid to hose and pressure seems much better now. Just need to dial in the fuel pressure again.

I'm running +20s with a stock logic module. Right now I am at 34PSI with vacuum line disconnected where it seemed to idle OK. Does that seem to be in the ballpark or should I up it to around 40?

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I'll take that cookie now;) Oatmeal raisin are may favoite:eyebrows: