IronicTonic

Hi Everyone,

I'm new to Rennlist. I purchased a 1986 944 NA about 3 months ago with the intention of learning more about Porsches and driving it for fun (I love well balanced driver focused cars). I've been a car enthusiast for as long as I can remember. Cars I've owned are the S2000, RX8, Lancer Evo 8, and now the 944 (not counting daily drivers). I've been lurking here for a while, absorbing as much info as I can because I plan to do all of my own work on the 944.

Recently the fuel line from the pump to the filter started leaking at the banjo bolt on the exit of the fuel pump. The thing was dripping about 5 gallons of fuel per day so I drained the tank and decided to replace all of the old rubber hoses, the check valve, the fuel filter, and the in tank filter. I kept the existing fuel pump because it appeared to be working fine, no idea if it's original though. The car has over 200k on the clock, but you would never know given how well it's been maintained.

Once I was done, I filled up with about 5 gallons of fuel and started the car. It started right up and ran for about 30 seconds before it sputtered out as if it ran out of gas. No matter what I do, it won't start now. The car just turns over endlessly. I'm guessing the car is not getting fuel, but I'm not certain why.

Any ideas what could be causing this? The only items I touched were the rubber fuel lines before the hard line.

I did some research but there didn't appear to be any threads that specifically covered this situation. I'm hoping someone can help point out a few areas to start looking.

Thanks,

Matt

Tiger03447

Nice looking car and welcome to the group, Matt..Can you hear the fuel pump run when you are turning it over? Check out Clark's garage videos on U tube..maybe they have something going..If you disconnect the line going to the fuel rail and catch it in a can/jar, do you get quite a bit or does it just dribble when the pump is on? It could be either a fuel pump problem or the DME relay which fires the pump..clark's garage has a video on how to jumper this out...keep us posted on how it's going..

mytrplseven

Since the DME (fuel pump) relay is only about $20 on ebay, and a common failure item I'd start there. Buy 2 and keep a spare in the glove box. Did you place the fuel filter in the proper orientation? There's an arrow on it for flow direction. I don't know if it matters or not but the arrow's there for a reason. You can also jumper the DME relay contacts (see Clarks Garage) and then listen for the fuel pump to start up. If it doesn't then you know where to go next. Good looking car. Good luck.

IronicTonic

I appreciate the suggestions, I'll pickup a couple DME relays for the fuel pump and I'll check the pump to make sure it's working. I'm certain the fuel filter was installed in the correct direction. I double and triple checked it during the install.

I'll get back and let you know if I find anything.

Oh, and one good thing, the car no longer leaks fuel. At least I'm making progress in that area!

Thanks!

Otto Mechanic

Well. It's still white.

Sorry, didn't mean to rain on your parade...

william_b_noble

the DME relay usually fails by having the solder on an internal circuit board fail - just resolder and save the $20, or add a jumper wire and have a permanent fix.

do you have fuel pressure? that is the quickest test - if not, your pump isn't running

IronicTonic

Thanks for the previous input.

I know it's been several months, but I've been busy with work and had little time for the car. Over the last couple of weeks I've been working to get it running and here's the rundown of what I've done:

-new DME Relay - Nope
-3 way jumper to replace DME Relay - Nope
-New fuel pump, check valve, both tank and inline filters - Nope
-Tested fuel pressure - Good, 2.5 bar when trying to start, pressure holds above 2 bar for a while, 10-20 minutes later - Nope
-tested injectors with noid light, signal is pulsing when trying to start the car, verified 12v from the injector wires - Nope
-manually fired injectors with a 12v battery, heard a distinctive click so they appear to be working - Nope
-changed spark plugs - Nope
-verified spark, seemed strong coming from the coil, but weak from the wires so I replaced the distributor cap and rotor, spark is stronger but seems intermittent at the wires - possible issue here - no change in starting - Nope

The plan is to check reference sensor and replace the spark plug wires next. Those are the next major items on my list. I'm getting some tach jump when trying to start it, but it's very small, almost unnoticeable. Would this indicate a failing reference sensor?

Another idea is to check timing.

Am I missing anything else? Could it be the DME itself?

I appreciate the help.

snb13

Have you ever jump started the car? Or charged the battery while still connected to the car?

plyhammer

Did you flip the wires when you reworded the fuel pump?

Jfrahm

The fuel pump may be jamming due to debris in the line, assuming you have a fuel delivery problem. You could have stuck injectors, or a bad DME relay or a host of other things.

If you have not checked the basics it's really better to check them rather than post on the internet so people can tell you to check the basics. A puff of starting fluid will tell you if you have everything but fuel. Checking spark is easy. Make sure it can jump 10mm.

carlege

Since this started with the gas tank being off. i might be inclined to see if something wasnt hooked up correctly, Tank not venting,

IronicTonic

I'm fairly certain I've covered the basics and then some. I checked each system individually. I have fuel pressure, injectors are receiving pulse (possibly stuck), I have spark. DME is working.

I am guilty of charging once while the battery was connected and I have jumped it several times while trying to start.

Jfrahm

Hmm, if you'd tested the fuel pressure that would have been good to mention.

Are the plugs wet after cranking?

If the plugs are wet it could be a blown FPR or damper or a bad ECU is rattling the injectors.

If they are dry I guess I'd still suggest a fuel flow test (run fuel out of the fuel rail into a container while cranking) and see if flow seems adequate.

mytrplseven

I have to say, the car looks cool in white (maybe because I have a 951 nick-named Casper, in white as well). If your fuel pump inlet is blocked, there should be a louder sound coming from the fuel pump due to cavitation and dry bearings or a failed pump. Checking fuel pressure is only part of the issue, you also need volume verification. So doing the delivery check detailed in the maintenance manual, or Clarks Garage, should be done. An obstructed fuel pump inlet could choke off fuel delivery while pressure would look normal. A new filter could still be contaminated if it was installed after the tank went back on. I had similar issue and the car would only barely run when I sprayed starter fluid into the intake.

Good luck with this. Keep us posted on your findings, please.

StoogeMoe

Yeah, I was about to say that. If that doesn't do anything, then fuel isn't your problem.