91 TR won't start

I'm sure Steve can chim in and give you better suggestions.

My take is to ensure that your battery is in tip top shape. Do you have a battery tender on it?

Also, the solenoid tends to be problem on the TR. I think you can get a 3rd party one for less than $50. It's really easy to replace since it's right on top.

Good luck, and let us know how it progresses.

 

I don't know to much about TRs but I would check and clean all the ground connections.

 

at one time i had some serious problems starting and keeping my TR going. The starter turned fine, but there was a problem with the cold start injectors cutting on...and staying on till car warmed up. I replaced a relay under the right hand fender and I have had no problems since. It cost 40 bucks for the relay ( bosch part) and thousands in trasporatation and wrong diagnosis.

 

I liked your problem a lot better when it was just a bad intermittent connection in the big cable somewhere from the "+" battery terminal to the solenoid (and the symptoms matched that pretty well)

First, please confirm that this is a US version TR (or give the version or engine family number).

If it is a US or late-euro TR (i.e., KE-Jet), my first suspicion (from your description -- "weakly running if you keep the RPMs up, but won't idle" -- is that right?) would be that you've lost the +12V power to run the injection system (which causes it to run like a much too lean adjusted simple K-Jet). On the large threaded stud on the starter solenoid holding the big battery cable there should also be a small GR (yellow/red) wire attached with it's own appropriately-sized lug. This GR wire supplies the +12V to run the injection system so, since you were just rooting around in that area, make sure that it's still a good connection, the crimping's OK, etc. (it's not unheard of to have the GR wire break from its lug).

If that all seems OK, the easiest functional test IMO is to measure the voltage on the R (red) wire at the water thermo switch when the engine is running (if only briefly) as shown in the jpeg. This R wire should be at +12V relative to a good ground (like the engine block or cylinder head casting) whenever the engine is running.

(If it isn't something obvious -- like a broken GR wire at the solenoid) Let me know if you pass or fail this R wire test and we'll go from there (i.e., into the triangular black relay box that Coach I mentioned).

PS it also wouldn't hurt to confirm that you've got spark on both banks during the brief engine running period too.
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We cleaned the bullit connector and now the car starts fine, except the car will start and only run for 3 to 4 seconds, and then dies. It is hitting on both banks and all cylinders.

I have unpluged the cold start valves with the same result. We have checked the ground wire on the starter and it is good. We have even checked the fly wheel sensors and they both OLMed out at 677 and 697. We moved the wires around while we were ohming them out and no ohms were lost, so they must be good.

We have checked every fuse in the fuse panel, which is brand new. We found one fault, and it was a brown wire coming into the fuse panel, lower drivers side. It only had power when the car was running, but you could see where the brown wire was over heating.

Right now we are thinking that it is the (overload fuel relay). We are now taking out the triangle box under the right fender and Frank is going to replace the relays. Does anyone know which one is the fuel relay or the bosch part number??? We hear there is no way to check the relay, just replace it.

Kelly

 

as I said earlier, it was a relay in that box that stymied my car. 928-615-124-01 may be the Bosch relay number, I had a Porsche dearlker fix the problem. The part cost 70.29 in 1998. Car starts and run well ever since.

It cost me at least 4 grand to have the car transported over and over, and finally a 600 mile trip one way to have it fixed. $70 part, 200 for labor, and thousands for hauling the car back and forth. It took several tries at different ferrari service shops before the porsche dealer diagnosed the problem...what memories!!!!!

 

Frank -- That's definitely trouble and needs to be corrected. This thread (post #30) has a description of how to troubleshoot the "C" O2 protection relay that should be supplying the +12V power onto the red wire when the engine is running:

http://ferrarichat.com/forum/showthread.php?p=135042248#post135042248

Start at post #29 (i.e., first confirm/deny the fuse condition on relay C) and then try the tests/measurements in post #30 (if the fuse is OK).

(It's all starting to come back to me ) There are many other evil things lurking upstream that relay "C" relies on to function properly so I wouldn't buy a new one just yet -- e.g., relay C relies on the tachometric relay closing which relies on the LH bank actually making spark -- have you confirmed that you have spark on both banks? (Although it's probably more than a 50% chance that you'll wind up there like Coach I experienced -- we've had several other trips down this same path on both K and KE systems that have ended in replacing the O2 protection relay.)

The "C" protection relay is the one in the black box with the replaceable fuse -- it's real purpose is protect the injection ECUs from an alternator over-voltage situation (and secondarily, to not power the injection system if it detects the ignition system isn't working). If the fuse is blown and keeps blowing, do not do the "jumping" described in that referenced post #30. Rather confirm/deny what the alternator voltage across the battery is doing during the brief engine running. If the fuse is OK, then you can more safely try the jumping stuff.

PS Please give version or engine family number.

PPS By not mentioning it, are you confirming that the GR wire stuff is all OK? (It can help me to know what's confirmed OK as well as what's confirmed not OK.)

 

It is definitely running on both banks

 

Then remove the protection relay C in the black box, add the 30-to-87 jumper wire to the socket, and try restarting:

If it runs OK and the terminal 15 wire/socket is +12V = relay C is probably toast

If it runs OK, but just for a few seconds, and terminal 15 is not +12V (during the brief running) = tachometric relay probably bad (since you report both banks are running -- i.e., it's not a coil/power module problem).

PS you wrote "the ground wire on the starter is OK" -- do you mean "the +12V GR power wire at the starter is OK"?

 

Yes, this thread:

http://ferrarichat.com/forum/showthread.php?t=8482 (post #17)

gives the details of what should be happening at the tachometric relay. If you jumper 30-to-87 at the tachometric relay socket, this should put +12V onto the ZB line going to the relay C terminal 15 socket (i.e., terminal 87 at the tachometric relay should be directly connected to terminal 15 at relay C).

Did it run a little "better" for the few seconds it ran?

Did you confirm that terminal 15 at the relay C socket was not going +12V during the brief running?
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That's a good sign...

No, it's not in the black box -- it's mounted behind the fuse/relay panel (see the jpg in post #18).

 

There's more than one "tachometric" type relay in the US TR electrical system -- as that description indicates, that particular tachometric relay in the triangular black box is for controlling the air pump (and you'd never detect if it failed ).

The tachometric relay that controls the fuel pump relays and the protection relay is the one mounted behind the relay/fuse panel.

 

Problem resolved?