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hard starting 86 745 turbo[ALL/1998] posted by Alex on
Wednesday, 27 August 1997, at 10:19 p.m.
Car takes long to start, cranks fine and then starts, but much longer than it used to. When warm starts right up. Have had the car for 6 months/9k miles, Have done tuneup stuff a while ago. (plugs, rotor, cap, wires, fuel filter.
Cranks for about 45 secs, then starts fine, Idles well at 7oo rpm, occasional "tic" in the idle. Seems to run fine, power good, smooth. No change in gas m
mileage. Thanks for any reply, Alex
Re: hard starting 86 745 turbo[ALL/1998] posted by Dave Stevens on
Wednesday, 27 August 1997, at 11:16 p.m.
Possible gummed up/faulty fuel pressure regulator (hangs off the injector fuel rail). There is a check ball valve inside. If it doesn't seat properly then fuel pressure is allowed to drop when engine is off meaning that fuel pump takes longer to build up cold start fuel supply. When engine is warm the fuel pressure is still up and so it starts right away. This matches your symptoms.
The long slow fix is to use an injector cleaner gas additive like Techron. The fast fix is to replace the fuel pressure regulator. The DIY compromise is to take the fuel pressure regulator off and give it a good bath in carb cleaner or something else that would remove the gas varnish and dislodge any grit around the valve.
Re: hard starting 86 745 turbo[ALL/1998] posted by Alex on
Thursday, 28 August 1997, at 8:07 a.m.
Thanks for your response Dave. I have run 2 bottles of the Techron already. I works Great-I did have some knocking before and the Techron has completely eliminated it. As for the regulator, maybe now is the time for the rising rate fuel pressure regulator. Anyway, I will take mine off/apart and see if aI can clean it better. Thanks all, Alex
Re: hard starting 86 745 turbo[ALL/1998] posted by Mark Klein on
Thursday, 28 August 1997, at 10:09 p.m.
Actually the ball check valve is located in the main fuel pump outlet. The regulator should also hold pressure but just has a plate pushed against the end of a tube. You can test if this is the source of your problem by clamping the fuel return line off when you shut hte engine off and leave it clamped off overnight. Crank the car and see if it cranks right up. It may crank right up and then shut off pretty quickly due to the excessive fuel pressure from the return line being clamped but this should help with the diagnosis.
I had a 740 give very similar symptoms and the problem was the main (noise suppression) relay mounted on the coolant reservoir. Never thought the relay would give the long cranking scenario, but it did.