Thread: STEPPER MOTOR THE CAUSE ??????????

You need to clean the seat that the cone on the end of the stepper motor seats in, I would use brake cleaner or carby/throttle body cleaner, make sure gasket is good and check the vacuum lines don't leak. Also get some Electrical Contact Cleaner and give the plug a good clean, also do the same to the MAF plug and if any of these plugs are loose open up the male pins with a straight O ring pick, best of luck, Regards Frank.

I am with Tank check that MAF plug and give it a good clean. Mine gave me intermittent grief with idle problems but since sorting it out I haven't had an issue. When the connections were marginal just giving it a wriggle would improve the idle from hunting and stalling to smooth and stable.

Originally Posted by Tank

You need to clean the seat that the cone on the end of the stepper motor seats in, I would use brake cleaner or carby/throttle body cleaner, make sure gasket is good and check the vacuum lines don't leak. Also get some Electrical Contact Cleaner and give the plug a good clean, also do the same to the MAF plug and if any of these plugs are loose open up the male pins with a straight O ring pick, best of luck, Regards Frank.

Thanks Frank, I'll give it a go, do you know what symptoms a faulty fuel pressure regulator would give, it sounds like it's starving for petrol on cranking or could that be the step/motor letting in to much air??????????

Is your fuel pump known to be good?

Originally Posted by sheerluck

Is your fuel pump known to be good?

Yes mate just replaced it.

Y'know, any and every component on an engine can fail suddenly. Instead of asking endless questions, do some diagnosis.

1. Remove the stepper motor, plug it back into the loom. Turn on the ignition, observe the plunger. Does it move? yes/no

2. Raise the base idle to keep it running for now. Either fit the stepper back in slightly unscrewed or unscrew the base idle adjuster. It's the 3/16 allen key screw in the pocket on top of the throttle body. Does it idle now? yes/no

3. Inspect the fuel pressure regulator. Is the little vacuum hose between it and the manifold connected? Is the hose split or swollen? Is there fuel leaking from the regulator out the little hose to the manifold?

4. Get a fuel pressure gauge and apply it to the schrader valve on the fuel rail. Is the pressure in spec when the engine is a. running at idle, and b. under acceleration? Example

5. You do have a workshop manual, don't you? Available in Dave's I.T. Shop.

Originally Posted by bee utey

Y'know, any and every component on an engine can fail suddenly. Instead of asking endless questions, do some diagnosis.

1. Remove the stepper motor, plug it back into the loom. Turn on the ignition, observe the plunger. Does it move? yes/no

2. Raise the base idle to keep it running for now. Either fit the stepper back in slightly unscrewed or unscrew the base idle adjuster. It's the 3/16 allen key screw in the pocket on top of the throttle body. Does it idle now? yes/no

3. Inspect the fuel pressure regulator. Is the little vacuum hose between it and the manifold connected? Is the hose split or swollen? Is there fuel leaking from the regulator out the little hose to the manifold?

4. Get a fuel pressure gauge and apply it to the schrader valve on the fuel rail. Is the pressure in spec when the engine is a. running at idle, and b. under acceleration? Example

5. You do have a workshop manual, don't you? Available in Dave's I.T. Shop.

Thanks for info bee utey, yes I have 3 manuals, and now thanks to you I also have a pressure test gauge, gees I wonder if you use the toilet paper with naughts and crosses ...... ha ha