Zero Fuel Pressure

[twright]

I am currently trying to resurrect a 1988 M3 with the S14 4 cylinder engine. This car has been sitting under a walnut tree and is really beat.

I'm trying to get it to start. I have replaced both fuel pumps and the wiring going to the in-take pump. The pumps now work and I have plenty of flow to the fuel rail. If I take the line off of the fuel pressure regulator and put a gauge on it, the pressure will pin the needle on my 100 psi gauge. If I hook the gauge inline with the fuel line and run the pumps, I get ZERO fuel pressure.

Does this mean I need a new fuel pressure regulator?



P.S. I was measuring the pressure at the rubber line that comes out of the fuel pressure regulator at the front of the engine. Is that the right place to measure this?

[moatilliatta]

Check fuel pressure before regulator.

You can kink the line after the regulator - Going to return to simulate a regulator.

[moatilliatta]

Also, watch out. The FPR can send fuel back into the vacuum line. I doubt enough to hydro lock a motor...

[mjweimer]

So you see high pressure at the rubber hose coming off of the fuel pressure regulator (the return to the tank) but no pressure at the hose feeding the rail (supply at the firewall end)?

With the supply hose to the rail removed (and placed into a suitable container) do you get a lot of flow with the pumps jumped/running?


Did you accidentally switch the supply and return hoses to the hard pipes at the frame rail (running back to tank and pump)?

[twright]

Ok, I have improved my measurement technique: I now have 45 psi at the fuel rail. Unfortunately, the car still does not start.

The fuel injectors are not firing . No fuel is coming out of any of them. What do I look for first?

[TobyB]

that the DME is getting power and crank signal.

t

[twright]

This thing has two Crankshaft Position Sensors and another one that is a Top Dead Center sensor. Are the CPS units the ones that tell the fuel injectors to fire?

[twright]

I finally got this thing running.

However, there is a bunch of brown non-magnetic junk in the fuel tank. I don't think its rust.

Can I clean out this stuff through the crossover tube holes in the bottom of the tank?

[jbontke]

Given that the car has sat a while, the tank is junk. If I were you, I would get a new tank or have the one in it cleaned. I got a car from a field and fought fuel issues until I cleaned the tank, had the injectors cleaned, and replaced all the fuel line.

[twright]

The real answer is "no". You can't clean all of that crap out of the tank. Just buy a new one. They're not that expensive.

[mjweimer]

100%. Considering the price of a new Spectra tank vs. the time it takes to "maybe" get it clean enough in place and then realize you need to drop it anyway to clean better....replace every time.

Good to hear that you got it running!

[twright]

I got it running. Unfortunately, the owner will not sell it to me. It's going back to him on Monday.

I was hoping to own an M3.

[mjweimer]

I got it running. Unfortunately, the owner will not sell it to me. It's going back to him on Monday.

I was hoping to own an M3.

Well at least he knows you are serious. Never know how these projects end up working out...he might not be up to the task of taking the next steps.

[dnguyen1963]

You should have bought the car before doing any of this work. The owner knows he has an M3 and now it's running he is not going to let go of it.

[twright]

He wouldn't sell it at any time.

He and I had made an agreement to sell the car to me before I did any work on it. He backed out the next day when I was on my way to get it. Working on it was my last ditch effort to own it. It didn't work.