Won't crank unless fuel pump fuse removed Caused by multi missfire 5,7 Q45t 97

[globus_it]

Just following the guide lines; I have searched and searched, read up almost every single topic associated with injection and spark distribution issues. Some of them are really close, so close that it kept me going untill 4:00am last night. But at the end here I am posting on my own behaf.

It all started with little almost unnoticeble stumbles (like if some one would drive by real fast) tiny single shakes kind of like that when I staoped at traffic lights or sat in idle.

After last emmision control service i desided that it's about time to look at my spark plugs (thanks God I did it after, would never pass it other wise). That's when everything desided to give in. First misfire on the right bank cyl.#6 caused by bad sparkcoil tested it by swaping it out with #2 and sure thing: computer confirmed the misfire switched to #2. So, replaced that along with my fuel filter and both knock sensors becase there were also codes for one of them and it did not have any current. By the time I got to those two little bastards neither one showed any signs of mulfunc.

I did not give it a second chance down in the galley. That's how low voltage electronix fail: first they play, second they go to sleep ... forever.

That fixed the misfire but not that little shake/poking . So I though it'll come out somewhere sooner or later. Sucks, but I was right and it was much sooner that I had a chance to save up on next part supply.

Anyhow, diagnosed misfire #7. Took out sparkcoils one by one wile at idle to see if all produce spark; and they all did just fine. So I took it to the next shop over. The guy does electronics diagnostics with OBDII and Consult readers for $40.00 max. Computer showed #7. Took out spark plug and it was all black and dry like if there was no gas in it at all.

OK, now. Manifold, get ready here I come again. Changed injector #7 and all of my problems went away even the problem. I figure that is caused by intermittant injection/sparkcoil mulfunction at an early stage. That never bothered me agian.

Until a few days ago it started to misfire again.

Now, the 97 Q45t with 135000K on is what I'm talking about and it wont crank to fire unless the fuel pump fuse is removed. It is located inside a box right next to drivers left foot. One of the techniques provided by the All Data. It dies immediately upon reinsertion of the fuse or pedal acceleration. So I was able to get to run bu doing just that and it seems like all of the spark coils are good and they all produce spark but I know that cyl. #5 and #7 are not combusting properly.

This evening I went out to my garage and guess what I couldn't get to run the way I did it the day before but it fired up the normal way. I jigled the MAF sensor and diconected it resulting in an immediate shut down but nothing that would draw my attention from that end of things.

To me it looks like an injection related issue may be the fuel pump is involved as well...

At this point the question is this: what is the relation between the fuel pump fuse and fuel supply to the cylinders? And why does it die suddently when I press on gas or put fuse back in

Any suggestions or even comments will give me food for thought so please go ahead...

Thank you for your time.
Modified by globus_it at 8:09 PM 1/5/2007

[globus_it]

Further diagnostics showed, that #5 in fact is in working condition: spits gas, spark is working fine. Before it did not cause any change in idle run upon removal of the spark coil, likely due to being next to the actual misfiring cyl #7.

Wild guess would be that the cheap injector that I got from online supplier was also rebuilt and gave in again.

The main question still stands though; I'm becoming to believ it has to do with foulty fuel pump or the fuel pump controller module.

I may be wrong...

[maxnix]

"Rebuilt" injectors are used injectors.

Start with new injectors then eliminate the next deficient component one at a time.

[globus_it]

BTW would someone know if the fuel pump will attempt to pressurise fuel line while TPS TB taken off and one of the injectors is taken out of the line, or will it stop. It occured to me to test if the fuel pump is pumping pressure to provide for the entire system; if it works at all.

[Q45tech]

Common for mechanics and poorly trained technicans to not think thru the results of pulling an injector out and the fuel rail emptying fuel into the cylinder.

[globus_it]

That is exactly the reason we're all here; to avoid common mistakes. And benefit from the knowledge of others.