84_944guy

Ok so it's a 1984 944 n/a it will start up just fine i give it gas put it in gear go a few blocks let the gas off to shift, and it wont go when i give it gas again it gets to 1200 then heads back to idle and will keep doing this unless i turn it off and start it again then it works for a little while then it will start doing it again about every block. I have already changed the contact points in the amf to be a little bit different still wont work right. anything is great sorry about grammar.

Terry B

Did you check the throttle position switches on the throttle body?
Just an obvious easy place to start.

peanut

sounds like a fuel delivery problem to me .

Is the car used regularly ot often left unused for a week or two ?

I'd start by putting a fuel pressure guage on the fuel rail and checking the fuel pressure valve and fuel pressure damper .

All you need is 12" of garden hose a cheap tyre pressure guage and a couple of jubilee clamps. you should see about 3 bar I think.

If you look at Clarks garage manual there is a proceedure which involves removing the DME relay and using a jumper to fire the fuel pump.

Also check that the air breather to the fuel tank is not blocked. Try running the car with the filla cap removed

J Berk

I agree with peanut.

This is similar to the symptoms I had on my old 84 NA when the fuel pump went bad....it would pump...just not enough preasure to run too far above idle...and occasionally crap out. Did this for a month or so before finally crapping out all together.

Mike C.

Maybe a plugged fuel filter also.

peanut

I suspected my pump at first but I did a fuel flow test which showed it could flow 150% max. I just attached a piece of garden hose onto the fuel rail pressure test nipple and put the other end into a 2lt coke botle. simples ....

The other possibility is a partially blocked filter (sorry Mike missed your post ) or a sticking non return valve in the pump.

I'd try a fuel flow test first cos it costs nothing.

Fuel Flow Rate Testing (Clarkes garage)
http://www.clarks-garage.com/shop-manual/fuel-04.htm

J Berk

not sure how that tests pump pressure?

You tested flow rate....my pump was so worn (I think it was the original pump) that while it would move fuel, it would not hold pressure.....

Flow rate = vol/time (ml/sec) Pressure = Force/Area (newtons/cm2)

peanut

you don't measure pump pressure to check your pump's efficiency you measure fuel flow rate which is differant. If you want to measure fuel pressure you need to use a gauge as I explained earlier.

If your pump didn't hold pressure then the non return valve had failed which is not indicative of a failed pump. You can just replace the valve