It worked great on the Dyno no issues
All I have changed is the fuel pump because it was leaking.. Walbro to standard Bosch 044
So Im not sure if I have a faulty pump or fuel regulator..?
It worked great on the Dyno no issues
All I have changed is the fuel pump because it was leaking.. Walbro to standard Bosch 044
So Im not sure if I have a faulty pump or fuel regulator..?
could be anything at fault! first point of call is spark plugs
plugs are clean and brand spanking new... less than 100 mile
gaps? boosted cars often want small plug gaps
If you haven't touched anything else then I would blame the part you have changed first.
And maybe even put the Walbro pump back in even if it is leaking. (a bit)
Is it a used Bosch pump? Is it a proper Bosch pump or a Chinese copy?
Have you cleaned it before fitting?
Same size inlets and outlets on the Bosch pump? Nothing silly like an adapter that's been put in to the replacement pump that's dropping the size down or something like that?
Definitely try the old pump back if you can - though be careful with the leaking fuel. The Bosch pump hasn't ingested some rubbish after swapping out the leaking one?
Gaps all ok Graham, thanks for the reply..
9.85 @ 145mph 202mph standing mile
https://www.youtube.com/watch?v=Ss_c7fML3rw
Stevie Not sur of the ID of the walbro it was spec'd for a cosworth and is 220 litre per hour
Plugs are iridium .7mm gaps
Fuel pressure seems to have dropped slighty but ive noticed that the pressure gauge on the fuel reg is leaking oil
Car was set up by MSD less than 40 miles ago, and ran great the only thing I have changed is the pump to a Bosch 044
In general, an 044 will flow about 80100lph more than the pump numbers you're quoting for the Walbro ( depending on what pressures you're quoting for of course ). So it will have a huge effect on the system. Your regulator may or may not be able to cope or need re-adjusted because of this increase in flow.
It would certainly make no sense for fuel pressure to have dropped moving to a pump that flows substantially more.
9.85 @ 145mph 202mph standing mile
https://www.youtube.com/watch?v=Ss_c7fML3rw
Other thing is pump inlet hose size - if the 044 is choked down to, say, 8mm bore it risks severe cavitation and loss of pressure and flow!
Inlet bore from tank should be no less than pump inlet.
9.85 @ 145mph 202mph standing mile
https://www.youtube.com/watch?v=Ss_c7fML3rw
does it stutter as it comes on boost then goes ok? 0.7mm plug gap could be your issue a lot of boosted engines will need a smaller gap .5 or .6
Last edited by Graham; 04-04-2017 at 11:53.
If it's under boost then plug gaps or fuel pressure would be my guess as well. Are you running the MSD wasted spark system?
In that case, as long as the plugs are gapped reasonably, you're not really going to get any better in terms of the spark. The general wisdom is that with the wasted spark setup you don't have to run the tiny electrode gaps that the tuned Cossies had to run in the old days.
It's an odd one. Have you got a way of trying the old pump again? If the pump is the only thing that has changed (and the problem followed the change) then it's got to be linked to that.
Have you spoken to MSD about your problem? Have you got a fuel pressure gauge inside the car? if not fix one up in some sort of fashion, even if it;s taped temporarily onto the windscreen. I had a problem with an Escort Cosworth Rally car with a similar situation, it turned out to be fuel surge when the tank was less than half full. Whomever had built the car had the fuel pump sucking directly from the Bag tank instead of fed via a swirl pot. I elected to fit an inbuilt one into the tank with submerged pump.
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