Help and Advice Please - Misfire

Changed the fuel pressure reg for an FSE valve which I modified as I was going to use it on my 21T. I think I need to get the pressure set correctly on it but it seems to have resolved the problem(fingers x'd)

ahh, but that may have just put on a band aid over a problem elsewhere, as the new reg may be overset to get the fuel pressure up to where it should be as the pump could be running below factory pressure for instance...

David Gentleman....official bringer of good news

[BIG_MVS]

Changed the fuel pressure reg for an FSE valve which I modified as I was going to use it on my 21T. I think I need to get the pressure set correctly on it but it seems to have resolved the problem(fingers x'd)

ahh, but that may have just put on a band aid over a problem elsewhere, as the new reg may be overset to get the fuel pressure up to where it should be as the pump could be running below factory pressure for instance...

bullocks

Think you were right Dave.

Right changed the fuel pump for known working one(off a 21t, slightly different but it fit) also changed the fuel filter for a brand new one. This ended up with the fuel pump being noisy as ever plus the misfires and cutting out were as bad as ever

We got the car back then reset the fuel pressure(was set to under 2 bar, set it to 3 bar) also reset the c/o reading. I drove home fingers crossed and had a couple of slight misfires but it seemed to drive OK. The fuel pump was again very noisy though so I think there is something else amiss!! Dave or anyone else any more ideas???? I will not be defeated!

Have you replaced those fuel filters yet? (both of them). If they're bunged up then that would explain your straining fuel pumps.

[BIG_MVS]

I replaced the main one Darren, where is the other one located?

Surely the pump would be noisy all the time if it was bunged up?

I still think your in the right ballpark Darren and it's something to do with the fuel pressure regulator, maybe the one I put on is faulty too!!

Your rear pump will whine if the feeder pump at the front isnt doing its job.....much like the whining you get when you are running out of fuel.

The fuel pressure reg will not make the pump make noises. If the pressure was well low, then the pump wouldnt be struggling anyway, and likewise if the the reg pressure was massively high, youd be pumping out loads of unburnt fuel out of the exhaust.

Have you checked the voltages and condition of the wire to each pump?

Also how did you set the fuel pressure?. If you pull the vacuum feed of the new regulator, you want to set it too around 3 bar....with the vac hose connected and on idle, it wants to be around 2.8.

The other fuel filter is at the front with the fuel tank.

PeterG had problems along similar lines and his filter turned out to be very old and gunked up. Voila problem solved.

The front one is the cheap one too.

[BIG_MVS]

Update - Still not fixed!

Replaced front fuel pump and still no joy, looks like there is no power to it??

Does anyone know if the pump is on all the time or comes on when needed?

Also my side repeaters are not working just wondering if they work off a relay connected to the front fuel pump???

Where should I take a feed from to power the pump if none of the above works?

Cheers

Have you looked at the electrical manual? or maybe that has confused you too???

[stephendell]

Have you checked all the injectors?

The front pump should be running at all times that the rear pump is. I think it only primes for a few seconds like the rear pump when the ignition is initially turned on though.

The rear pump will certainly howl if the low pressure pump doesn't work. The car will drive for maybe 6 miles after the front pump stops as there is a 1.5L swirl pot it feeds, that in turn feeds the main pump.

After the car has been parked for a while some fuel will gravity feed from the main tank to the swirl pot through the front pump, and let you run for short time again.

The correct original front filter is actually a very fine mesh that only stops big rocks. I admit I have fitted a standard paper type fuel injection filter in the front position that I will change every 10 000 miles, that will stop very fine material.

[BIG_MVS]

Have you looked at the electrical manual? or maybe that has confused you too???

Now now Simon.. I must admit to being totally rubbish when it comes to mechanics of cars, also being extremely lazy when reading instructions!!

I'll have a study this week.

[BIG_MVS]

The front pump should be running at all times that the rear pump is. I think it only primes for a few seconds like the rear pump when the ignition is initially turned on though.

The rear pump will certainly howl if the low pressure pump doesn't work. The car will drive for maybe 6 miles after the front pump stops as there is a 1.5L swirl pot it feeds, that in turn feeds the main pump.

After the car has been parked for a while some fuel will gravity feed from the main tank to the swirl pot through the front pump, and let you run for short time again.

The correct original front filter is actually a very fine mesh that only stops big rocks. I admit I have fitted a standard paper type fuel injection filter in the front position that I will change every 10 000 miles, that will stop very fine material.

That makes perfect sense Alan, and is exactly what is happening. I have replaced the front fuel filter already.

Stephen - Not checked the injectors yet but if the front fuel pump isn't to blame they are next on the list.

I have some suprises on the way for my car which means I will have a spare set of injectors that were professionally overhauled and cleaned about 500 miles ago...and they are the slightly larger 191cc ones!