97-01 Q45 fuel pump controller

[Q45tech]

T3 had a interesting case where 2 previous shops [dealers] had changed fuel pump, filter, lines, regulartors , fuel pump again , controller again on a 1997 Q with little success.

Byron found the bypass resistor burned along with its wiring resulting in low idle and cruise fuel pressure [<15 psi] which became normal under acceleration and WOT.

[bullittandy]

Could this be the idle stumble? Where is the bypass controller on a Y33?

[maxnix]

The "bypass resistor" to which Q45tech is referring from his description is on the FPCU board.

[maxnix]

The "bypass resistor" to which Q45tech is referring from his description is on the FPCU board.

Now I am wondering about its location.

Surely there is another problem causing both to burn out (assuming the first failed also) if it is on the FPCU board.

[bullittandy]

I just swapped the fuel pump control and the bypass resistor from my parts car (no idle stumble) and it did not solve the idle stumble on my 99.

since I've replaced the plugs the stumble is almost constant-AND STILL NO MIL!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1

[Q45tech]

The only way to replace spark plgs is to unscrew and man handle and stress the spark plug boot on the coils. An increase in severity [after spark plugs] shows a coil or coils are the problem.

I expect that many problems are time delayed after a spark plug replacement from lack of finesse.

[qship96]

Yep, why you should apply some type of lubricant to boots to make future removal uneventful. I bet Byron learned to charm the boots off those plugs without damage.

[maxnix]

You know, I never have experienced that problem on any of my cars.

[bullittandy]

Oh, I wish the patron saints of NICO had been with me on my repair!!

I will probably break down and order 3 more coils in order to replace the entire passenger bank of coils.

If a coil failed as a result of the way I removed them (extremely gently) then these things are terribly made.

[maxnix]

I doubt that occurred.

But just dirty intake paths have the same symptoms on the VH45DE, and on my VH41DE despite having been cleaned less than 20K miles previously.

[Q45tech]

Use Google to find specs on various US manufactured coils on plug system.

It is scarey when they quote a 60k or 100k usable life [less than 4,000 hours of life] ..............it is though they expect you to change coils when you replace plugs just like you did in the 1970's [coil, wires, points, dist cap].

[bullittandy]

Well, I pulled the trigger and bought another 7 (already had 1 new) brand new coils in order to fix this problem. ($600-ouch!)

I will find the idle stumble threads and post the results therewhen I get them installed.