544DRS

I thought I was getting somewhere with my '83 944 restoration. Now...this!

I drove for about 80 miles, then parked the car in the garage for the night. Next morning, no start. The engine turns over, lights and buzzers do their thing, everything electrical works, but the car won't run.

My searches reveal that I should see if the fuel pump is working. Aux. fuse box #2 is fine. I replaced the DME relay with a new one. Still, no luck.

So here's my question: What procedure should I follow to check my fuel pump to see if it's getting electricity? Does the starter need to crank, or do I just turn the key to "ON?"

One of the reasons I've been inspired to work on this car is that it always started so well...

Nick

Spidey944

Will take 2 people to test, unless you just jumper-wire the DME relay port. Remove the shielding for the fuel tank at the rear of the car (May have to drop the strap holing the tank). Then using a test light or multimeter hook the wires to each side of the fuel pump connector and have someone crank the car over (assuming you didnt jump the DME relay) This should tell you if you have power or not going to the pump. If you dont have power then you know that your problem is b4 the pump wiring, if you do have power, but no pump activation, then chances are the pump is no good.

Another way is to jump the fuel pump directly with a 12v source, but I dont like doing that as there is no protection device involved.

544DRS

Thanks for the help, Doug. I'll get a helper and go for it. Before I do, though, do you think I'm on the right track? That is, my car has always started fine for the six months I've owned it, and this is the first time something like this has happened. It's failed to start only once before, but only because I neglected to connect the ground wire to grounding point #1, something I checked right away.

And, I don't "smell" fuel, as if I would if the engine flooded. I haven't checked to see if the engine is getting a spark. Do I need to do that before I do the test you've detailed?

Thanks again for your help,

Nick

Spidey944

Spark is always the first thing I look for, well, that and fuel registering on the fuel gauge..... The pump only runs while cranking/running, not key on/engine off. You could just have someone put thier hand on the pump cover and crank the car and see it it's humming, may save you some time, but if it's not humming, then you would still need to check for power.

Scott at Team Harco

Check out the jumper wire instructions at Clark's garage. Takes the guess work out of whether the DME relay of fuel pump are working. If all is good you will hear the fuel being pumped to the fuel rail.

Or.... you may have the joy of going through what I just had to do. My speed sensor failed. Therefore, no spark. Had the great fun of snapping off both the speed sensor and the reference sensor as they would not budge from their respective holes. Then proceded to damage one of the bolts that hold the bracket in place. Took a couple of days of working with a torch and several new vice grips to get the last bolt out. Even then, the (diagnostic) RPM sensor was somehow broken off. Fortunately I had some good help from JPK and my girlfriend's car. We just bought her a 944 a couple of months ago. Made it real easy to just take parts off her car and swap into mine.

Ordered three new sensors (will have one as a spare). Got my car running again last night.

Will be getting her car in ship-shape the next two days so we can take it to the Fest as well....

544DRS

Thanks again, Doug. I need to read up to learn the best way to check for spark. Fuel registers on the fuel gauge just fine.

Nick

544DRS

I'm looking for those instructions now! Thanks!

Hope that's not my problem. Did your problem show up the way mine did? I drove my '83 944 the night before, put it away for the night, but the next morning...no start.

Thanks,

Nick

Scott at Team Harco

Yes - no warning. Car ran fine to get me to my distination and back during my lunch break. Went to start the car to go home after work - no go.

544DRS

My fuel pump does see power. I measured the voltage as my son cranked the ignition. Voltage went up to a little over 6VDC. I'm unsure what the fuel pump wants to see, and I thought it'd want 12VDC, so this might be an issue.

So, here's a summary...

• Car ran fine during an 80-mile run with several stops. Parked the car for the night.
• Next morning, car wouldn't start.
• Car cranks fine, battery voltage fine, gas gauge works, lights/buzzers work.
• Fuel pump fuse (Aux. #2) is fine.
• Replaced DME relay with a new DME relay.
• Voltage at fuel pump present (approx. 6VDC).
• Tank 3/4 full of 76 Premium 92 w/no ethanol.
• Car is now on jack stands awaiting further testing.

Here's where I could use some help:

1. Should I trace the fuel pump's wiring to see why it's seeing only 6VDC? Would a weak ground cause this?
2. When I went under the car to check the fuel pump's wiring, I found the rubber boot insulators for the fuel pump wiring pulled back, and the connections are pretty dirty.
3. If I need to replace the fuel pump, do I have choices available to me, (e.g., size, pumping ability, or whatever)?
4. Is my next step a fuel pump replacement, or should I perform more diagnostic tests (and if so, what are they)?

Thanks again for the help,

Nick

vro944om

i actually pulled mine of yesterday , i had the same problem, to fully check if it works, take an old car battery or something 12v under there, disconnect the leads and wire the battery to it, if it runs.. its a wiring problem, if not, its a pump problem. you can even check by taking off the engine-side of the fuel pump and let some gas drip to see if it smells burned. (burned out pump)

544DRS

Thanks. I think I'll do that: I just need to find my test leads with the alligator clips.

Still, I'm wondering why I'm reading 6VDC, and if that'll keep the fuel pump from operating.

Nick

vro944om

i actually got 2VDC, but it was the fuel pump, idk if my wiring is messed up too, but the fuel pump was deffinately burned

544DRS

Okay, I guess I'll replace the fuel pump, if further testing tomorrow reveals it ain't working.

For those who've replaced a fuel pump, what advice would you give a guy who's never done it before? That is, what tools should I have available to make it go smoothly, and is there anything else I should change out while I'm doing it?

My car is an '83 944.

Thanks,

Nick

jpk

There are more than a dozen things that can cause the car not to start. Before blindly replacing anything, start with the basics, and the things that are easiest to check. It takes fuel, air and spark to make the engine run. You need to confirm which one you're missing.

1) Do you have spark? it's really easy to check...
2) Check the fuel pressure at the rail (a guage isn't very expensive)
3) Are the injectors firing? (you can get a "noid light" to plug into the injector harness to check).

One of the best refrences for the DME system and how it works (especially the early 944) is www.frwilk.com

544DRS

Thanks. You're so right. I'm doing a bit of testing tomorrow to see what's going on.

My previous post hoped to find out "everything" I'd need to consider/anticipate if/when I replace the fuel pump, just so I could be prepared and expect the unexpected!

Nick