Printable View
I can't say that I think a wasp nest is terribly likely, but I will certainly add fuel pressure check to my list. I would have liked to do it earlier but i didn't have a gauge. It's not the first time I wish I had a fuel pressure gauge though, so I bit the bullet and ordered one.
Thanks for all the suggestions!
Ok so a bit of progress this weekend, but still not quite there...
Checked the timing marks on the balancer were correct - all good
Double and triple checked the firing order - all good
Checked fuel return hose for blockages - all good (my fuel pressure gauge hasn't shown up yet so I couldn't check the pressure)
Some things that did seem to help...
Removed and disassembled the distributor, found that the fly weight assembly at the bottom wasn't engaged into the little plastic retainer properly, causing a bit of free play (the springs were still in place). Also the Pick up and reluctor seemed a bit sloppy. Cleaned it all up and re-assembled it properly and re-set the timing. Timing is now sitting perfectly on 8 degrees BTDC.
Cleaned both MAF sensors with MAF cleaner spray. Now it seems to drive as well with the 5AM sensor as it does with the MAF unplugged.
BUT
It's still not right...
Idle is better, but still hunts a little bit.
Still running rich, plugs covered in black carbon.
Power seems OK once the revs are up a bit, but it is very lazy from low RPM. If i hadn't checked the timing I would have thought the timing was about 10 degrees too retarded.
If anyone can think of anything else keep the suggestions coming!
I would really like to check a known good MAF... anyone in the West Melbourne / Geelong area that would lend me one?? :D
Some progress this weekend:
Triple checked firing order - all good
Checked fuel return hose for blockages - all good (fuel pressure gauge hasn't turned up yet so couldn't check pressure)
Checked timing marks on balancer corresponded to actual TDC - all good
Some things that actually helped a bit:
Removed and disassembled distributor - found mechanical advance unit wasn't located correctly in the bottom (spring were in place, but the whole unit had a bit of slack) re-assembled correctly - timing now sits steady on 8 degrees BTDC
Cleaned and tried both MAF sensors - got the best results using the 5AM from the Discovery - I think that it runs and drives as well with the cleaned 5AM as it does with the MAF disconnected
BUT
Still running very rich - plugs covered in black carbon
more driveable from idle, but still very flat and lazy from low RPM - If i hadn't checked the timing myself I would have guessed the timing was too retarded. Power picks up when the revs come up, but if you floor it from idle it takes a good second before things start to happen.
SO I am starting to wonder if maybe the cam is a tooth out to the crank... I'm was fairly sure that it went together correctly, but now I am starting to second guess that...
ALSO if anyone In the West Melbourne / Geelong area has a known good MAF that I could borrow to make sure that isn't the problem... :D
If anyone else has any ideas keep them coming!
Has anyone ever tried to check the cam timing through the distributor drive hole with an inspection camera / borescope / endoscope? Does it work?
Failing that, anybody have specs for a factory cam so I can check valve lift and try to work out if my cam is in time? I counted the teeth on the cam gear and got 40, so 360 degrees divided by 40 gives me 9 degrees per tooth, if it were a tooth out I should be able to see it by measuring valve lift...
In some good news my fuel pressure gauge arrived, so I should be able to rule that out as an issue this weekend.
If the cam timing and fuel pressure is OK... I guess my last option is to buy a new MAF... but I hate doing "swapnostics", I like to prove something is faulty if possible.
Once again any other suggestions are very much welcome.
So that fuel pressure gauge was worth the investment!
Once I had the gauge sorted out (the gauge had a blockage in the hose - cheap eBay POS) I found 60 PSI in the fuel rail! Almost double where it should be.
Next I tested the regulator by running the return hose into a bucket and found that the pressure dropped to a nice and stable 36 PSI...
Next test was to run the return hose from the back of the car via a rubber hose into the fuel filler and take a short test drive - all running perfectly!
(I had already blown air through this hose last weekend so I was pretty sure the problem wasn't here)
So then came removing the bumper to remove the tow bar to remove the fuel tank. I found that whilst I could blow air through the return line in the tank, it was quite difficult... I pulled the pump out so I could see in the top of the tank and didn't see anything obvious.
Shoved some mig wire through the return line and it came good! I didn't see anything come out of the end of the return hose inside the tank, but it became easy to blow air through.
So there you go, I thought I should report back what the issue was in case anyone else searches for the same symptom - might save someone some time in the future.
The return line gets blocked in the nipple in the tank, with rust I assume. There have been posts about this issue in the past and BeeUtey was on it.
Glad you got it sorted!
DL