Quote:
Originally Posted by Jonny H
If it misses when ‘lugged’ in 5th gear, low speed (35mph) with WOT then do check spark interval. Coils can change behaviour when warm.
|
Not to worry I don't think it's a spark issue!
It turns out the easy check I was going to do turned out not to be so easy. Well, easy to do but hard to make sense of..... I mentioned I did a fuel pressure test yesterday. Simple enough, put the banjo bolt adapter fitting in one of the lines that goes to the pump, plug in the gauge, 12 or 13 psi, same as I had on the test rig.
Today, I did a volume test - 30 seconds to fill a litre bottle. 120 litres per hour should be plenty. However when I did the test I simply disconnected the return line to the tank and put a new hose on the fitting and fed it to my test bottle. I noticed the fuel pressure (that the MFI pump head would see) was zero.
So, I kinked the hose, the pressure shot up to over 20, and stayed there, once I unkinked the hose. It also stayed there when I turned off the electric fuel pump? When I had the fuel system mocked up on the test rig, it would always behave exactly as expected, so there is something definitely wrong here.
I took the "fuel overflow valve" off and tested it with an air regulator, no issues there, so I'm thinking clogged fuel filter.
The symptoms I am experiencing are consistent with fuel starvation. It's a little tricky "reading" the situation with the AFR, I thought it was spiking towards lean because of a misfire, but I guess that's the effect, not the cause, after all.
I did install this in the line between the fuel pump and the filter console - Aaron Burnham advised me that he wouldn't rely on the filter console for filtration so I added a filter - it's supposed to be a 30 micron screen so should catch some particles.
It's relatively microscopic, however, so I think it might be easily clogged if there is for some reason debris in the fuel system.
New tank, new tank strainer, new lines, new pump, new filters..... I can't imagine how this has happened. Will report back tomorrow when I have a chance to get that filter apart and assess the condition.
Fingers crossed, because it should be an easy fix.