Fuel Management

Hello from down under. We have a customer who has a stroker 7.2ly M100 981 engine built for him and we need to make it run. We had a local company overhaul the injection pump including making some allowances for the additional capacity, but it has all turned to crap.... After two attempts they just can't get the pump right.

- cold it over fuel like mad, black smoke at idle
- once warmed up (if the plugs haven't fowled in the meantime) we can get a reasonable fuel mixture
- but when we put it into gear it goes full rich again
- then to make the whole problem extra confusing it leans right out the minute you try to accelerate to the extend that it pings and lean misfires.

We have bene using this company for years to do our pumps and have never had an issue with them until this pump.

Thoughts? Is this why AMG only went to 6.8lts? Or in other words is it impossible to make the 6.3lt pump work with 7.2lts?

Any assistance would be very much appreciated.

Thanks, John Green.

I'm all to aware what a pain in the arse it is to swap the pump but have you tried a known good pump in the car?

300SEL 6.3 #2723, my first classic Benz 3.5 #8659, my second. 2 to go...

I would think that your at some sort of limit on the injector and valve (on the pump) limit.

Am surprised that electronic FI wasn't considered. It seems marginally less impossible than expanding that pump's capacity.

-CTH

John ,

Have you checked the cold-start-valves on leaking ???

Who did the engine John and installation of the peripherals?

Options:

Weak fuel delivery pump when hot, plus leaking cold start valves, plus failed injector warm-up thermostat, plus trans vacuum leak, jammed idle screw when someone touched it while running, jammed rack... so many options with any combination occurring together. I suspect it should start, run, and idle even if all of the fuel delivery is set back to the original specs - just a little harder to start and a lean idle, but then lean off under load. Then, blocked fuel return hose etc..

regards

Michael

I bumped into really long injectors a few month back. I mean like 8-10cm long, with a straight, thin tube. If somebody can make that, they can make them curved. And if they can, then a stock motor can be given EFI in a straight-forward, reversible way.

When I have the time (ha!), I'm going to see if that can done with an 220se manifold I have here with its injectors poking out through the tubes.

-CTH