Your help needed
My wife’s 1987 740 GLE wagon will not start any more. It did this once before last year when it was extremely cold but we found that plugging it in allowed it to start. This was only curing the symptoms not the disease.
The car is over fueling and flooding as near as I can tell as when it did run there was lots of black smoke and you could smell fuel. Now it is just cranking and cranking with intermittent firing but will not run.
When it was running its fuel economy was terrible as it was using way more fuel than it used to.

There is NO OBD to give me any indication where to look for the issue. This is why I am appealing for your help and suggestions.
We have replaced numerous parts trying to fix this problem and I’ll list them here.
We have replaced the following:
Coil
Spark plugs
Spark plug leads
Coolant Temperature sensor
Air filter
Anti-knock sensor
Throttle position switch
Flame trap hoses
Power stage
Fuel pump
Fuel filter
Oxygen sensor
Fuel pump relay
Noise suppression relay
Rear Exhaust muffler and pipe
Cleaned injectors and fitted new seals
Cleaned Air Mass sensor

Any suggestions as to what I should look at or if your car did the same thing and a particular fix cured it I would be very grateful to hear.
Thanks,
Steve

Hi, I’m sure that someone here might be able to help, however you’ll get a much wider audience, and lots of qualified help on:

Forums.turbobricks.com

The appropriate section is Mechanical - maintenance and non performance.

Good luck.

My immediate guess is the engine wiring harness, as these things are known to dissolve with time and will cause all sorts of random strangeness with the engine. A thorough check of all circuits would give you a good idea of what's going on. Another suggestion would be the fuel pressure regulator - I've had one fail rich, but not rich enough that the oxygen sensor couldn't compensate, however it was a bit tough to start and when it went into boost and the oxygen sensor kicked out, it fell flat on its face. Yours may be more severe. Finally, if it's absolutely HOSING the fuel to the cylinders, you may have washed all the oil from the rings and have reduced compression which is making it even tougher to start.

Sorry for the delayed response.
Matt

740 GLE would be non-turbo? Possibly PRV6?

Regardless, Matt's advice is always pretty sound. My first guess would be fuel pressure regulator. While I haven't had direct experience with a bad one, I've read more than a few times about people having similar symptoms and the FPR was the culprit.

If/when it starts, does it continue to pump black smoke out the tailpipe?

Pylon, the car is a non turbo 4 cylinder sohc red block engine. Fuel pressure regulator is suspected and will be tested by substitution of the one on my '89 740 to confirm one way or the other.

Thank you all for your replies.
Stephen

Hi Steve,

Lots of good ideas above.

You say you've replaced the coolant temperature sensor; just double checking that you replaced the rear (hard to reach) one and not the front one which is only for the temperature guage. Once out they're easy to check with a pot of water on the stove, a thermometer, and an ohmmeter. Specs at different temperatures are online.

If you want to borrow a fuel pressure regulator to experiment with, I have several used ones. Would be nice if it was easier to check running fuel pressure on the car, but there might something in your shop that would adapt. I suppose a badly leaking injector could be a possibility? I've never run into that, but CTS and FPR for sure.

Hi Chris,
yes the temperature sensor that I replaced was the one at the back under number three intake branch of the manifold (not the forward temp gauge one).

I had the car running yesterday and it ran much better but was still running a bit rich. I substituted the pressure regulator from my car and it ran much much better so I am now TRYING to buy a new one but so far have had no luck from our usual shop suppliers as they say the part is "unavailable" (NAPA, Worldpac, Altrom etc). Places that do have them in the USA won't ship to Canada

If you have a serviceable FPR would you be willing to sell it?
Cheers,
Stephen

iPd has them and they ship to Canada

https://www.ipdusa.com/catalog.asp?CAT_ID=992&categorycrumbs=988&searchwords=

Rockauto is probably the cheapest at $63 Canadian ($45 US) plus shipping. Their shipping varies but includes brokerage/taxes and is often quite reasonable and fast. You're welcome to try one of mine, if it helps we can discuss if you want to buy or just use until a new one comes in.

It's fixed!!!
We purchased a new fuel pressure regulator from LORDCO parts as we'd 'not tried them previously. I phoned them three days ago on the off-chance that they might be able to get one and to make a long story short they actually had one in stock here! It is the same Beck/ Arnley one that we were trying to get out of the USA. It was more expensive than we would have liked but in the long run we don't have exchange, brokerage, duty and shipping to contend with which made it about 25% more in cost by our way of reckoning. The wife said "just get it".

I installed it last night and the car fired up very quickly and ran smoothly. I gave it a test run and it went very well. The wife used it today and was ecstatic.

I'm glad that adventure is over which just leaves the other "honey-do " items on the car's list of requirements.

Thank you all for your suggestions, they were most appreciated.
Stephen

Good to hear!

For the record, LORDCO parts are the best damn thing to come out of BC, including Ryan Reynolds. They're the only place to go while travelling. I will admit that I *STILL* haven't been to ours though.