[Author Prev][Author Next][Thread Prev][Thread Next][Author Index][Thread Index]
Re: Failure Mode From Hell Solved
I too installed a new fuel pump on my 87 5ktq. I ordered it from
Carlsen and the part number is 443 906 087 BE. This is an updated
Bosch unit that is longer (or taller) than the original pump. This
new unit came with the check valve, and to my surprise the
instruction sheet states NOT to use a noise damper. The kit provided
a nut to cap the fuel line. All works well and the noise level is
much quieter than the old pump.
Another note is that the new pump has a different screen design.
It's made of a green poly material (whatever poly type material
resists gasoline) and it protrudes from the bottom of the pump. It
has more surface area than the previous metal screen did. I believe
Mike at Carlsen said that this is the 4th generation pump. Maybe
they finally got it right?
87 5ktq - 185k miles
> The failure mode from hell is finally solved (its been a long 3 weeks)
> after replacing almost my entire fuel injection system. After numerous
> hours troubleshooting a low fuel pressure problem and subsequent
> dismantling of my fuel distributor (which I never got back together -
> had to buy a junkyard unit for $130) I discovered, with the help of many
> E-mails back and forth from Scott Justasin (thanks Scott) and Phil Payne
> (thanks Phil), that the fuel flow rate was too low. I then concluded
> that it had to be either a restriction in the fuel line or the new fuel
> pump was defective. here is what I found: I am assuming that my Mitchell
> manual 0.71 qts. in 30 sec. is spec.
> 1) Removed fittings at press. accumulator and ran pump - flow was same
> as at fuel dist (very low about 1/2 the 0.071 spec.).
> 2) Removed fuel pump and did a bench test on FP itself.
> 3) With press. damper removed and check valve in place pump output was
> great - over twice the 0.071 spec. (fuel came out so fast I could not
> even get a good measurement).
> 4) With new check valve and press. damper in place flow was low - 1/2
> 5) With old check valve and damper in place flow was great - over twice
> spec. (my old check valve won't hold any pressure so using it is out)
> 6) Upon inspection of the new check valve and damper assy. I noticed the
> length of the new check valve (the section that screws into the damper
> through the banjo fitting) is about 0.025" longer than the old check
> valve. When this is screwed into the damper that extra 0.025" is
> bottoming out (or coming very close) against the internals of the damper
> causing a flow restriction.
> 7) To verify this I put an additional (0.050") washer (2 washers total)
> on top of the banjo bolt to take up this 0.025" and with new check valve
> and damper flow was great. - over twice spec.
> I then put everything back together with an extra 0.030" washer in place
> and I have rock solid 92 psi of system pressure.
> Car is running great - I think I was having a bad case of 15psi
> withdrawal (my 79 F150 4X4 long bed, super cab - read slow pig - doesn't
> do a whole lot for my need for speed!!!!!!!!!!!!)
> I think I might post some lesson I learned along the way in the near
> 87 5KTQ