Hot fuel and detonation, some q's - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

anakha · 12-31-2002, 16:45

I have an unshielded bosch in-line fuel pump in my ED's engine bay and I suspect that as the engine heats up it is overly heating the pump and thus the fuel. I have been experiencing some detonation under load at mid to high revs and am suspecting it is fuel system related as the car showed lean on the dyno when a wideband meter was hooked up.

Has anyone else found heated fuel causing a problem? Also what would be recommend recommend to shield such a pump? As a note I do not have coated headers and coating them is not an option in the short term.

12-31-2002, 20:29

Put the fuel pump near the tank. Or you can buy some heat shield wrap at most auto parts.

If it is leaning out at higher revs it is probably caused by the extractors - very common. Larger jets or smaller air bleeds in your carby. Or if it's a Holley go the next size up power valve.

How about retarding your timing by 4 degrees as a short term cure - you don't want to damage your engine.

WBT56 · 12-31-2002, 23:04

As above, put your pump as close to the tank as possible. It probably isn't the pump as such, but the fuel before the pump will be under partial vacuum, so it vaporises very easily, causing supply problems.

ebxr8240 · 01-01-2003, 19:48

Pumps push better than pulling.. When I bought my Bosch pump I was well warned that any crap in fuel can wear them fast..
Heat wrap or whatever its called is an option though astheticaly can look crude but works..Sheilding looks better..

This car is EFI....
Maybe an adjustable fuel reg ????

Might pay to check that both pumps are working esp the std one..

anakha · 01-01-2003, 22:02

Thanks for the input so far guys.

I have already tested the fuel pressure at idle at the Schrader valve on the fuel rail and it tests ok. I have yet to hook up the tester between the two pumps to see if the in-tank pump is not 100%. Also planning to run a fuel flow test to see if the expected volume is coming through.

Couple of side notes. The EEC-IV did not report any relevant faults in the KOEO and KOER tests, nor the cylinder balance test. Also the fuel filter was replaced ~30,000km ago, which is well within the recommeded service period of 80,000km (not counting for any exceptionally crap loads of fuel of course).

ricthewheelie · 01-01-2003, 23:05

check your oxygen sensor sometimes they do funny things