NEED HELP! 1987 3.2 won't start

mthomas58 · 04:38 PM

Started with usual suspects. Replaced DME relay today and then fuel pump (orig) .....both on my to do list anyway. Still won't start. Could not hear old fuel pump running with ignition on and can't hear new pump either. Ideas?

Speed and reference sensors both replaced year ago at time of engine swap along with new dizzy cap, rotor, plugs and plug wires. Are any of the fuse panel relays associated with the fuel pump or just the DME relay under the driver seat? Could it be the Motronic box? Mine is a reman unit already....not sure when replaced.

Thanks

McLovin · 10-22-2010, 03:11 PM

I'd pull a plug and see if you are getting spark.

I'd try a shot of starter fluid to see if it is a fuel issue.

I'd also give the CHT sensor a check with a multimeter to see if you have proper cold resistance.

For the 20 minutes it would take to do those 3 things, it can help narrow things down quite a bit.

McLovin · 10-22-2010, 03:13 PM

Also, you said you replaced the DME relay today. Was it starting fine with the old relay? If so, put the old relay back in and give it a shot. Many people (myself included) have gotten new DME relays that were bad right out of the box (esp. if its a URO one).

mthomas58 · 10-22-2010, 03:17 PM

Quote:

Originally Posted by McLovin

I'd pull a plug and see if you are getting spark.

I'd try a shot of starter fluid to see if it is a fuel issue.

I'd also give the CHT sensor a check with a multimeter to see if you have proper cold resistance.

For the 20 minutes it would take to do those 3 things, it can help narrow things down quite a bit.

CHT sensor replaced also at time of engine swap. I don't know yet if I am getting a spark, but as indicated above I do not appear to be getting power to the fuel pump. Just don't know why.

mthomas58 · 10-22-2010, 03:19 PM

Quote:

Originally Posted by McLovin

Also, you said you replaced the DME relay today. Was it starting fine with the old relay? If so, put the old relay back in and give it a shot. Many people (myself included) have gotten new DME relays that were bad right out of the box (esp. if its a URO one).

I was not starting with the old DME Relay either. My new DME Relay came from the local dealership - spendy but I needed it immediately.

galileo · 10-22-2010, 03:22 PM

battery?

mthomas58 · 10-22-2010, 03:24 PM

Quote:

Originally Posted by galileo

battery?

Battery is fine - Optima Yellow Top < 1 year old - cranks like a mother!

mthomas58 · 10-22-2010, 03:26 PM

Car has been running fine with no previous problems. Retuned from trip late last night......would not start this AM (fortunately this did not happen when I was out of town)

techman1 · techman1's Garage

Do a quick dist cap/rotor check, after you check the fuses in the trunk?

mthomas58 · 10-23-2010, 05:20 AM

Have checked all fuses in trunk and engine bay and dist cap. All good. Have Motronic box out now checkng for cracked solder joints (PITA for these 50 year old eyes)

NY91184 · NY91184's Garage

Was the Reference Sensor you replaced an OEM Bosch unit? Ive heard of people having problems with non OEM ones. The original reference sensor on my 84 just stopped working about a month ago, leaving me stranded with no fuel/spark. The easy check for that would be to see if the tach needle bounces while the car is cranking

kodioneill · kodioneill's Garage

You have to check and see if you lack spark or fuel. Do not use starter fluid on a gas engine ever. Pull off a plug wire, short it to ground and see if you have spark. If you have spark then check fuel pressure.

stlrj · 11:36 AM

Quote:

Originally Posted by mthomas58

Car has been running fine with no previous problems. Retuned from trip late last night......would not start this AM (fortunately this did not happen when I was out of town)

Was it parked outside in the rain?

mthomas58 · 10-23-2010, 12:35 PM

Quote:

Originally Posted by stlrj

Was it parked outside in the rain?

No, not rain related.

mthomas58 · 10-23-2010, 12:43 PM

Could not find any obvious solder cracks on the DME cirucit boards so I buttoned everything back up. Still no power to the fuel pump so I called AAA and flatbedded it to the Dealership for them to troubleshoot the problem.

Thanks all for the help. I've got to get my DD back on the road quickly and promissed Mrs PAPAMRK I'd finish the hardwood floors upstairs this weekend. In 4 years of daily driving, this is the first time I've had to get towed.

ischmitz · ischmitz's Garage

The fuel pump only runs when you crank or when the engine is running. Did you check power WHILE cranking?

mthomas58 · 10-23-2010, 02:18 PM

Quote:

Originally Posted by ischmitz

The fuel pump only runs when you crank or when the engine is running. Did you check power WHILE cranking?

No. I did not know that. I thought the fuel pump was energized with the ignition on. In any event, after replacing the fuel pump and DME Relay (both needed to be replaced anyway for peace of mind), I am beyond my diagnostic capabilities.

Dan Owens · 10-23-2010, 02:41 PM

Did you check the fuel pump relay in the trunk on the fuse block? The red one

mthomas58 · 10-24-2010, 04:29 AM

Quote:

Originally Posted by Dan Owens

Did you check the fuel pump relay in the trunk on the fuse block? The red one

Per my check of the Bentley Manual, there is no fuel pump relay on the panel (none labeled as such in the picture anyway)

Dan Owens · 10-24-2010, 06:10 AM

Mine is the first position on the right and is not labeled on the block cover. I presumed you have one too as the part is listed for 74 thru 89 I think. I had the same issue and it was the relay. Here's the blurb from the hosts parts site:

Relays are a very common source of failure in the 911. There are several different relays used within the 911, and all are subject to failure after many years of service. Before suspecting your wiring or your components, be sure to check your relays. Before you decide to replace your fuel pump, make sure that your Red fuel pump relay, which is located on the relay board within the front trunk area, is functioning properly. Also be sure to check that your DME relay, 911 (1984-89), is functioning properly. Pelican recommends that you carry an additional DME relay, which is located just under the driver's seat, with you at all times. It is wise to have at least a spare on hand, so that you can check the proper operation of the one that is already installed within your 911.