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**robertisaar** · 06-01-2011, 10:19 PM

60,000 miles is a pretty common life for the timing belts.... i'd be replacing it anyways.

**Schurkey** · 06-01-2011, 11:10 PM

What is the cranking compression?

For that matter, what is fuel pressure; and do you have spark at the plug end of the plug wires?

**RollinonZ34** · 06-02-2011, 07:46 AM

Yea, i knew i was pushing my luck with that Belt, but my illness, Cancer, that i am now free & clear of left me with no energy to do anything...I feel 99 years old...lol..But now i got no choice, disabled for the most part & broke, can't buy a new one...going outside in a few and pull that cam cover and take a look.

**RollinonZ34** · 06-02-2011, 07:55 AM

Schurkey, i don't even know how to check compression, not much of a mechanic, and i would think it is getting spark or i would not have heard backfire, i think...i did replace wires, spark plugs, and coil pack not too long ago w/quality stuff..a/c Delco not too long ago so i think good there. Was wondering would bad gas make it not crank & backfire, even though took it out yesterday and drove like a champ on that same gas. Just wondering if Computer or fuse or whatever else might give it signs of Timing off?

**RollinonZ34** · 06-02-2011, 07:48 PM

Removed Cam covers and belt looks very good..no cracks and still thick. I then went to replace fuel filter and drain any old gas out. The thing is i took filter off and just a few drops of gas came out, and that was under pressure, as i did not relieve pressure first like some do. Anyway i then with the fuel filter still off and line open, turned key thinking fuel pump would blow out gas in the tank. But nothing? I then replaced the fuel pump relay and still nothing. Question is shouldn't fuel have sprayed out of the line from tank when i turned motor over for about a minite or so. Does this sound like Bad Fuel Pump and are they a bitch to change as i have no idea? Thanks for any help...

**Schurkey** · 06-03-2011, 12:47 AM

Originally posted by RollinonZ34 View Post

with the fuel filter still off and line open, turned key thinking fuel pump would blow out gas in the tank. But nothing? I then replaced the fuel pump relay and still nothing. Question is shouldn't fuel have sprayed out of the line from tank when i turned motor over for about a minite or so. Does this sound like Bad Fuel Pump and are they a bitch to change as i have no idea? Thanks for any help...

Originally posted by Schurkey View Post

For that matter, what is fuel pressure

The fuel pump should run for ~2 seconds when the key is turned on. It should run continuously with the engine running. I think it should run with the engine cranking but not running.

You should have been showered with gasoline.

Time to diagnose the fuel pump electrical circuit. Could be as minor as a popped fuse; could be defective wiring, could be a defective pump, could be...lots of things.

Doing the PROPER method for fuel pump replacement means dropping the fuel tank. Some folks have decided that it's a better (???) plan to chisel a hole in the trunk and pull the pump assembly from above. Then they somehow "repair" the access hole.

**RollinonZ34** · 06-03-2011, 12:32 PM

Schurkey, i agree with you totally... I am trying to pinpoint as easily and cheaply as possible. I did replace the fuel pump relay, but that did not do it. I for the life in me cannot find the Fuse though? Only thing i saw was in glovebox and at bottom it did have a slot for fuse and said Fuel pmp. i think it was, but no fuse was in the empty slot. and not even any copper siding in it to hold fuse and make circut? Anyone know where that Damm Fuse is for the Fuel Pump Please let me know ASAP...There has just got to be one somewhere.. Thanks again,

**walterdude** · 06-03-2011, 01:17 PM

There are 2 boxes with fuses and relays under the hood.. 1 is near the coolant tank,, you have to pull the diagonal brace to get at that one.. Another should be right around the positive aux connection.... That's how my 99 Lum is.... The 93 Z34 is covered up and I haven't looked at it in a while, but, I think it's the same.... Check out a manual....
Good Luck,,,
Tom....

Edit:
A quick look at a schematic only shows relays for the fuel pump under the hood, no fuses... Sorry...

**RollinonZ34** · 06-03-2011, 02:42 PM

Well i did finally find Fuse, it is on passenger side over computer, and the Fuse is marked ECM BAT is a 20 Amp fuse and feeds many things. I guess the hunt is on now with wiring to the tank...got my fingers crossed as i do not want the hassle of dropping the gas tank - do not know how to replace pump, and also what to replace, just the pump or the screen, any gaskets or o-rings, etc. and also the money to replace it all. And don't worry Schurkey, not gonna cut up the trunk to access, unless i run into major problems doing proper way, that is after i find out the proper way....lol.. Thanks everyone for input.

**pocket-rocket** · 06-03-2011, 04:51 PM

If it comes to the pump, you replace the sending unit. It has the pump in it, along with the screen (or should at least. if you replace the pump, replace the screen as well) and the big o ring around the sending unit will come with the new one. Some do come with a new pigtail to splice into current wiring.

**Schurkey** · 06-03-2011, 05:58 PM

Originally posted by RollinonZ34 View Post

Well i did finally find Fuse, it is on passenger side over computer, and the Fuse is marked ECM BAT is a 20 Amp fuse and feeds many things. I guess the hunt is on now with wiring to the tank...got my fingers crossed as i do not want the hassle of dropping the gas tank - do not know how to replace pump, and also what to replace, just the pump or the screen, any gaskets or o-rings, etc. and also the money to replace it all. And don't worry Schurkey, not gonna cut up the trunk to access, unless i run into major problems doing proper way, that is after i find out the proper way....lol.. Thanks everyone for input.

You buy any decent brand of fuel pump and everything is included except the screen/sock prefilter. Be VERY CAREFUL because many fuel pumps are now sourced from China; and you don't want a junk pump because they're so difficult to replace.

BEFORE you drop the tank, find the wiring harness and do the electrical tests.

**RollinonZ34** · 06-05-2011, 03:20 PM

I did electrical the best i knew how. I found and disconnected the harness or plug where it goes into the tank. I then took an ohm metter and checked for continuity. There were 4 wires 1 purple and 3 black i think. Checkecd by putting 1 lead on purple and then other lead on the other 3 one at a time. I had closed circut on just 1 set of wires, and nothing on the other two. I am guessing that since my fuel guage still workes properly that that was the good pair, and the other was open circut or bad pump. I hope this was correct as i could not check for Voltage as i am by myself in the stix and had no one to turn key while i was under car with meter. So correct or not i went ahead and ordered Pump w/sending unit. Thanks Pocket Rocket for telling me about get sending unit as it comes with Pump/filter and everything needed for the job. I ordered it (spectra premium) from Rock Auto, and it costed about the same for whole kit as just the Pump i was looking at to buy. Once again, this site is "The Best" @ helping with these cars and 3.4DOHC on the net! Also, thank you Schurkey for info, i did also order big o-ring and round bolt or whatever it is called that you turn on top of tank to remove assembly, but ordered that at nearby Autozone for much cheaper..no S/H. Thanks again for info as i still need to do the dirty work and drop the tank...not looking forward to it as i am fairly handicaped and very difficult to do things anymore, but i will get it done in baby steps if needed...lol...Any more advice, please chime in...Much appreciated..

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Timing question - with backfire

Question : Timing question - with backfire

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