760, 89 6cyl stalls on start after getting up to temp.

Tiki · Post by **Tiki** » 15 Jun 2009, 23:12

My 89 760 GLE with the B280F 6 cyl. stutters, bucks and stalls with the slightest load once it's up to temp. You have to drive almost ten miles before it acts up. When the temp gauge is at the mid-point, normal for this car, it starts to act up. It runs OK as long as you keep moving, just won't accelerate quickly. But once you stop it won't accelerate from a stop. Sometimes if you are lucky you can rev-drop it and get going. This means you rev it up in neutral and drop it into gear, as soon as it moves try again. But man is that hard on the car! When it's cold it runs great. Once it acts up if you let it set for an hour or two it will cool off and run great again. It does start when hot but it's hard to get it started.
I suspect something is keeping the spark from advancing, that's how it feels.

It did this a couple months ago then stopped. Now it's back. At that time I did not make the temperature connection. I thought it was fuel feed. Like it could be starving for fuel. I replaced the fuel & air filters. Replaced the pickup screen in the tank. Verified both pumps are working. I inspected the Air intake box to make sure it was not stuck on the preheat. I checked a bunch of other fuel related items but can't recall now.

If anyone has some insight or suggestions I would greatly appreciate them.
Thanks!

Post by **vegasjetskier** » 16 Jun 2009, 10:05

Bad coolant temp sensor?

Post by **billofdurham** » 16 Jun 2009, 11:26

Here are some other things to check:

760 Trouble Shooting.pdf: (26.96 KiB) Downloaded 145 times

The '89 760 non-turbo should be fitted with the On-Board Diagnostic (OBD) unit in the engine compartment so you can check for fault codes which may give a better diagnosis.

Bill.

Tiki · Post by **Tiki** » 17 Jun 2009, 23:15

Thanks Vegas, I was leaning towards the coolant sensor. In the great scheme of parts that one is not so expensive so I will start with that.

Bill, thanks for the troubleshooting guide. There was a couple items on there that I had ruled out because in my wisdom I couldn't see how they were related. But seeing them on the list makes me wonder about my wisdom;) So if the coolant sensor doesn't pan out I'll go over the list. I still have to build me a blinking light to check the On board. This particular model doesn't have the under hood unit where you check, just a red/yellow lead.

Right now the car drives fine as far as the bus stop in town. So i'm using public transport. I won't work on it again until the weekend.
I'll let you know what I find. Thanks again for the replies.

Tiki · Post by **Tiki** » 24 Jun 2009, 23:04

Update: I haven't fixed it yet.
I did replace the coolent sensor. It did not fix it. So I went to the electronics store and bought an LED and some conectors and built a test light for the ecu. At first I didn't get any codes just a random flash which I understand to be the knock sensor. Then sitting in my driveway with it in gear and my foot hard on both the brake and gas, it started to flash six times. This is the plug wire sensor. So I checked first the plug, the gap was wide but not excessive. Then checked the wire which was old but not broken. Then the cap and rotor. Well, the center electrode was disintegrated in the cap. there was major erosion on both the cap and rotor. So I'm giving our sponsor fcp a try. Ordered a Cap, rotor and plugs. I'll build some new plug wires as well. I don't think this will fix my problem but it's a have to fix anyway sorta thing.

I'll keep you posted when I fix it.