89 VN s1 V6 hard to start - SOLVED

[the_boozer]

does the alternator charge light work? if no the alternator isn't charging

 

[Callumbh5]

Definitely check the alternator. In an ideal world at about 1800rpm you should be seeing 14-14.4volts at the alternator (measure between the positive output stud and alternator body), then measure the battery voltage and they should be almost identical (allowing for a small voltage drop in the wiring). At idle you might find the voltage will be down a touch depending on how much electrical load you have on.

Thanks mate, I’ll look into this tonight and see what I come up with.

 

[Callumbh5]

Hey lads,

So I cleaned all the earthing points in the engine bay, cleaned the fuse box as well, when running and at 1800 rpm the alternator showed 14.48 volts and the battery was slightly less.

Still haven’t managed to fix the problem.

Car still is hard to start but drives fine and idles fine when cold but once warm every time I let off the gas it almost dies and if I’m stationary if I go to Rev it or put in gear it’ll die sometimes, I almost have to keep the gas on to keep it from dieing whilst driving around, any other ideas?

 

[Immortality]

Well the alternator sounds fine. I'm almost wondering if you have a vacuum leak. Check the vacuum hose that goes to the MAP sensor, these can go hard/brittle with age and the MAP sensor is rather important.

Have you cleaned the throttle body? The IAC controls the idle, maybe something going on with the IAC stepper motor.

 

[Callumbh5]

Well the alternator sounds fine. I'm almost wondering if you have a vacuum leak. Check the vacuum hose that goes to the MAP sensor, these can go hard/brittle with age and the MAP sensor is rather important.

Have you cleaned the throttle body? The IAC controls the idle, maybe something going on with the IAC stepper motor.

Hey man so I just did a diagnostic check got one flash then two so no issues there, it’s probably worth noting when it starts with a small rev added it starts misfiring pretty bad.

I’ll have a look at the vacuum hoses now

 

[Callumbh5]

Well the alternator sounds fine. I'm almost wondering if you have a vacuum leak. Check the vacuum hose that goes to the MAP sensor, these can go hard/brittle with age and the MAP sensor is rather important.

Have you cleaned the throttle body? The IAC controls the idle, maybe something going on with the IAC stepper motor.

I have also replaced IAC and TPS and CAS

 

[OldBomb]

After 3 flashes of OK (12), it may still thow a fault code. Let it run longer & see if it changes.

 

[Callumbh5]

After 3 flashes of OK (12), it may still thow a fault code. Let it run longer & see if it changes.

Hey mate I did that and nothing,

I manage to find the map sensor hose was split, will fix it tomorrow when i can get some more vacuum one hopefully that sorts it

 

[Callumbh5]

Hey mate I did that and nothing,

I manage to find the map sensor hose was split, will fix it tomorrow when i can get some more vacuum one hopefully that sorts it

Sorted the vaccum leak out and car started first pop for the first few times, I’m starting to think my fuel pressure regulator has gone as I pulled the vaccum hose off and fuel came out it has also gone back to not starting properly and once started it doesn’t fire on all cylinders for a few moments and noticed the fuel gauge will stick for a sec before jumping to where it needs to be would the FPR cause that? Still cuts out whilst coasting also

 

[Immortality]

Fuel coming out of the vacuum hose for the FPR is a sure sign it's stuffed.