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Racer29 · #21 10-22-2007, 07:26 PM

.. I had a similar problem with my 87. There are two sensors at the flywheel. Same part number. TDC and engine speed RPM. One sends a signal to the fuel pump to pump fuel.
Easy replacement through the left rear fender well. If you don't move the holding bracket it is a drop in replacement.Worked for me...good luck I hope this helps

paul · #22 10-22-2007, 07:41 PM

Thanks Kevin - I will put those items on my things-to-check list.

The next thing I plan on doing is to check for spark since that is pretty fundamental. Don't know why I didn't think of it earlier when there was plenty of daylight left ..

Dr K · #23 10-22-2007, 09:09 PM

Quote:

Originally Posted by paul

Don't know why I didn't think of it earlier when there was plenty of daylight left ..

Ahhh, but it's easier to see in the dark.

Peter

Jazzbass · #24 10-22-2007, 09:10 PM

Easiest way to test the fuel pump is to put a fuel pressure gauge on the left side FI rail on the engine. This will tell you if the pump is working and that it's putting out enough pressure (> 3bar IIRC). If the pump isn't working it could be:

1. Bad pump
2. Bad DME relay
3. Bad DME
4. Bad sensors as Dave indicated

The DME will only turn on the fuel pump when the ignition is on AND either (a) you're cranking the starter or (b) the engine speed > 400 rpm.

If you don't have a fuel pressure gauge, listen for the pump whine when someone is cranking the engine. Alternatively, jumper the fuel pump on using a jumper wire to the bottom of Fuse 2 and Fuse 3 (fuel pump fuse). That'll turn the pump on regardless of the DME or relay. That can help you figure out if it's the pump or the DME.

Make sure all the connectors in the engine bay are good and closed. As discussed earlier in this thread, these connectors like to deteriorate over time. If the speed or the ref sensors (left side of the engine, bolted to the manifold) are undone, that's a problem. Likewise any of the connectors on the main FI parts - throttle body, etc. Sounds like you're good with a meter; almost all of these sensors can be tested. Make sure:

- Throttle position reads fine
- AFM is fine
- Speed sensor resistance is in range
- Position sensor is in range
- Cylinder Head Temp is in range (this is a likely culprit, BTW, esp if you still have the old 1 wire sensor)

I like to test the sensors at the DME connector itself to make sure the entire circuit is functional. BTW, was the spare DME relay you put in new or used?

- Bad coil - test resistance.

My guess? One of these:
- bad fuel pump
- CHT sensor

FWIW, although it wouldn't have helped in this case, hopefully you can see why having a spare DME relay IN THE CAR is a good idea. Nothing worse than paying $$$$ to have your car towed just so you can install your spare $30 relay.

tdatk · #25 10-22-2007, 09:22 PM

Quote:

Originally Posted by Jazzbass

Easiest way to test the fuel pump is to put a fuel pressure gauge on the left side FI rail on the engine. This will tell you if the pump is working and that it's putting out enough pressure (> 3bar IIRC). If the pump isn't working it could be:

1. Bad pump
2. Bad DME relay
3. Bad DME
4. Bad sensors as Dave indicated

The DME will only turn on the fuel pump when the ignition is on AND either (a) you're cranking the starter or (b) the engine speed > 400 rpm.

If you don't have a fuel pressure gauge, listen for the pump whine when someone is cranking the engine. Alternatively, jumper the fuel pump on using a jumper wire to the bottom of Fuse 2 and Fuse 3 (fuel pump fuse). That'll turn the pump on regardless of the DME or relay. That can help you figure out if it's the pump or the DME.

Make sure all the connectors in the engine bay are good and closed. As discussed earlier in this thread, these connectors like to deteriorate over time. If the speed or the ref sensors (left side of the engine, bolted to the manifold) are undone, that's a problem. Likewise any of the connectors on the main FI parts - throttle body, etc. Sounds like you're good with a meter; almost all of these sensors can be tested. Make sure:

- Throttle position reads fine
- AFM is fine
- Speed sensor resistance is in range
- Position sensor is in range
- Cylinder Head Temp is in range (this is a likely culprit, BTW, esp if you still have the old 1 wire sensor)

I like to test the sensors at the DME connector itself to make sure the entire circuit is functional. BTW, was the spare DME relay you put in new or used?

- Bad coil - test resistance.

My guess? One of these:
- bad fuel pump
- CHT sensor

FWIW, although it wouldn't have helped in this case, hopefully you can see why having a spare DME relay IN THE CAR is a good idea. Nothing worse than paying $$$$ to have your car towed just so you can install your spare $30 relay.

As usual excellent tech reply Chris

paul · #26 10-22-2007, 10:39 PM

OK

Tested for spark - used extra plug as well as one of the AutoZone spark tester - we got spark.
Definitely smell of gas from muffler outlet - but does this mean pump is working? If not, I will jumper the pump and listen for it and also check cap/rotor etc. when I get back from work tomorrow.

Thanks for all of the tips/suggestions.

btw - the spare DME relay is brand new from Pelican

paul · #27 10-23-2007, 04:47 PM

Jumpered the fuel pump via fuse panel (battery hot to fuse #6 bottom). Expected a mechanical whirring sound - instead just got a thud. Appears to be a bad pump. I thought there was the gas smell last night but must have been residue. From checking other posts, the odor is obvious.

So, is it unanimous that the culprit is the fuel pump??