Capri Technical Forum:

Hi, I'm new to these forums and was hoping someone could help with a problem of mine.

I have an 82' 2.8i. It was in my grandma's garage for about 15years. We've re-built the engine and pretty much everything mechanical. The old metering unit was siezed so I replced it with one from an xr4i that was running.

The car starts on the cold start valve (direct fuel feed), but stalls when trying to run from the injectors. The pressure backs up all the way to the fuel pump.

If we release all the pressure in the fuel system the car starts but runs v.v.lumpy. If you then switch the engine off it won't start again as the pressure has built back up.

Checked for air/vacuum leaks, kinks in pipes, injectors have a nice spray and warm-up regulator is returning fuel.

Any suggestions would be greatly appreciated.

Hi, is the return side working ok. Do you get fuel returning to the fuel tank via the return pipe.

Very good question. As far as I can tell, yes. When I release the bangoe there is fuel there. However, I haven't taken this pipe off the tank to check as its crimped in place...

I think I'll need to do so to ensure the fuel is returning. I'll let you all know the outcome.

Thanks.

you aint got the flow and return pipes round the wrong way???

The flow and return are both indicated by small arrows on the metering... You can't really get them wrong. The car actually runs if we release the pressure thats built back up.

Basically the pressure is pushing the plunger up, thus the metering plate down... the engine tries to draw air but can't lift the metering plate to allow air through because of the pressure (i think).

Have a look here, may give some clues.
http://www.auto-solve.com/mech_inj.htm#MFI04

Thanks for the link, good stuff. I've seen it before but seemed to have more detail this time?!? Strange.

Fuel Return;

Ok, the fuel is returning through the return fuel line, however it isn't getting into the tank... It allows a small seep into the tank, no return leak, but for some reason the fuel under pressure isn't getting in...

There must be a none return valve that has seized?? or similar. All suggestions would be and are greatly appreciated.

barkin wrote:The flow and return are both indicated by small arrows on the metering... You can't really get them wrong. The car actually runs if we release the pressure thats built back up.

Basically the pressure is pushing the plunger up, thus the metering plate down... the engine tries to draw air but can't lift the metering plate to allow air through because of the pressure (i think).

i got this problem when i put a new metering unit on my car,any ideas how to fix it,when i get home im gonna check to make sure the fuel is retuning,

I'm pretty sure the problem with mine is to do with the fuel return into the tank...

Things to check with yours could be;

Fuel return, you should get a minimum of 750cc every 30secs
Fuel Pump working and voltage greater than 11.5v
Even spray from the injectors
Warm up regulator is returning fuel
Metering unit plunger hasn't seized (they tend to if they've been sitting for too long).
Bleed pipes and check for kinks and air leaks.

Let me know if you get a solution as this could help with solving my problem.

when you say you get a trickle from the return at the tank what is it like near the metering head? is it a trickle there too???
if it's not and its gushing out, is the pipe from the metering head to tank blocked or kinked? as this would cause a pressure problem

There is fuel gushing out of the return pipe at the tank.

I sprayed wd40 into the connection at the tank at it seem to go into the tank, however when i started the engine with the clip off but the pipe on the tank it blow off the tank.

have you tried blowing down a piece of pipe fitted to the return on the tank

one thing to try, sounds crude,

put the return pipe into a fuel can and see if the car runs ok,
if it does then the fault is with the tank

I've put an air compressor on the return into the tank and it wasn't getting through.

I've also tried running the car with the return off and its not running... It starts on the cold start then seems to stall after about 5 secs due to lack of fuel. I thought this was because the system was pressurised?? Or am I looking at replacing the fuel pump aswell again... hope not.

when the engine stalls can you hear the pump running?

Yes, definately running... however it is struggling because of the pressure backed upto it. Makes an unhealthy noise it may need replacing even tho it was new when we re-built the engine... hoping its ok tho.