G50 : Hesitation, Bucking, Jerking, Loss of Power, Choked Acceleration ...

[maxnix]

Pictures are too out of focus to tell much. Check the particular solder joint carefully to see if it is melting then reforming upon cooling.

[goody90q45]

In all reality, it might be easier to take the FPCU out and see if the common solder joint is bad... If its OK, then youll need to take the fuel pump out and see if its getting 12 volts TO THE PUMP.

Lino- Since you've got the FPCU and FP out now it should be easy to check. The FP only has 2 leads. I was able to run jumper wires to a battery and confirm that my spare FP was working. If your pump doesn't run when you jumper it directly to a battery the FP is fried.

Next check that you've got power when you turn the key on. I think you've already done it at the connector following the steps in the FSM, now you can do the same thing to the two leads where they connect to the FP. You should have zero voltage with the key off and 12v when you turn the key on.

Don't worry about the FPCU for now. If the FP is good you don't need the FPCU (if you've jumpered the FP to ground) and it can be bypassed until you get your car running.

[lino]

Wes asked me if the fuel pump relay was clicking and I said no. I was wrong about that. I had someone turn the key in the ignition while I held the relay in my hand, and it clicked. I wasn't able to hear it from the driver's seat. Sorry Wes.

Before I discovered this, I changed the "green" fuel pump relay for a blue colored one that looked the same to me. Then I had someone turn the key in the ignition while I held the relay in my hand. I felt it clicking. Then I swapped back the original green fuel pump relay and tried it again, and it did click in my hand.

Lino- Since you've got the FPCU and FP out now it should be easy to check. The FP only has 2 leads. I was able to run jumper wires to a battery and confirm that my spare FP was working. If your pump doesn't run when you jumper it directly to a battery the FP is fried.

I checked the fuel pump by jumpering it directly to the battery and it does run. It was slower than when I grounded out the fuel pump. That could be because my battery charge is low. I hooked up the charger to it now. It must be drained from the interior lights being on the last few days of me working on the car.

Btw How much pressure should the fuel pump put out?

Next check that you've got power when you turn the key on. I think you've already done it at the connector following the steps in the FSM, now you can do the same thing to the two leads where they connect to the FP. You should have zero voltage with the key off and 12v when you turn the key on.

I got zero voltage with the key off and something like 7v or 8v, where the battery is weak. It only stayed at that voltage for 4 seconds and then dropped back to zero.

[goody90q45]

I checked the fuel pump by jumpering it directly to the battery and it does run. It was slower than when I grounded out the fuel pump. That could be because my battery charge is low. I hooked up the charger to it now. .....Btw How much pressure should the fuel pump put out?

Correct me if I'm wrong but the fuel pump should run around 35psi when you first turn on the key but with the engine off. With the engine running thepressure should be in the 40-45psi range.

It sounds like you're fuel pump may still be working if it ran during the first few seconds after you turned on the key. Now I would suggest checking the FP with it jumpered to ground by unplugging from the FPCU and running a wire from the lower left pin in the connector (see the pic I posted) to ground. To do this, the sending unit should be reconnected to the FP but not reinserted into the gas tank.

If the FP still works, and you were able to get your Q running and drive it down the street, it makes me think that you lost your ground to the fuel pump during the short test drive. Do you have an alligator clip you can grind the tip off of to be sure you're getting a good, solid connection to the pin?

[Q45tech]

When a Q gets flat bedded in the first thing we do is jump the pump to ground to drive it into shop. If this doesn't work we push it in, check the FP fuse and replace the pump and FPCU as a set...............................this proceedure solves 99% of the hundreds we have done over the past 10 years.

My 90 Q is on FP #3 and my records show this one was changed in 2002 at 235k so the current FP has 75k and I am beginning to hear the noise again, so #4 will probably get installed this Summer.

To me pumps and FPCU are just like spark plugs, hoses, belts, thermostats, injectors, shocks, and suspension parts ....................all wear items that get replaced FREQUENTLY.

THERE ARE MULTI HUNDREDS of individual components that get replaced [or should be replaced] during a 17 year life.

Currently tracking down an intermitent ocassional failure of #2 cylinder.So far changed the spark plug and coil for #2 [not it] so #2 injector gets replaced today..........hope it's not the harness or any harness or ecu.

When I changed KS and rehosed the fuel system last summer I kept looking at the brittle cracked injector harness but skipped it...........

[goody90q45]

When I changed KS and rehosed the fuel system last summer I kept looking at the brittle cracked injector harness but skipped it...........

Tech, Tech, Tech, tsk, tsk, tsk. Not following your own advice. You're banned from the board for the next 60 minutes. Go stand in the corner and think about what you've done.

Just kidding Boss!!

[lino]

I just got back from a shop who tested my fuel pump and the verdict is in...it's toast. The pump's not pumping. Question now is if I buy a new fuel pump, , can I use the FPCU for a week or so if it's still working? (Basically until I'm able to get a used one shipped to me)

[96Qowner]

Wow, that was a toughie to chase down! Congratulations. I wouldn't worry about the FPCU for the time being. It sure won't hurt anything to test it with the new pump first. It's probably fine.

[Jesda]

WOOHOO! I love good news.

[lino]

Wow, that was a toughie to chase down! Congratulations.

Thank you. I ordered the fuel pump from the local dealer. I can't handle the delay with customs and all the surcharges that come with transborder transactions for this problem. The car has been off the road since last Friday and it could take 3-7 business days to arrive with no guarantee at a cost of $450-$500 Canadian. So it was not worth it for me to buy it from the US. What a shame since Joe sells it for $235.

The dealer price here is $608 Canadian including the tax and I should see it by tomorrow or Thursday. The parts manager said he'll give me a better deal when I pick it up.

I wouldn't worry about the FPCU for the time being. It sure won't hurt anything to test it with the new pump first. It's probably fine.

I'm going to do just that. I'll try the new pump and see what happens. Hopefully, the FPCU is ok. My only fear now is if the FPCU damages my new fuel pump. One person I spoke with, believes that if the FPCU is faulty, it could damage the fuel pump and he also believes that there is a possiblity that the FPCU could have been the problem all along. He thinks that it could have been sending the wrong signal to the fuel pump contributing to it's death.

[pbedrosi]

Lino, I also have your symptoms but intermittently. I though the source of this was a bad MAF connector. I remember a post regarding this (joe has a repair kit). Let us know if the fuel pump solves your driveabilty problems, I'm sure it will at least fire up.

[lino]

Lino, I also have your symptoms but intermittently. I though the source of this was a bad MAF connector. I remember a post regarding this (joe has a repair kit). Let us know if the fuel pump solves your driveabilty problems, I'm sure it will at least fire up.

You could buy from Joe or from ebay:

http://cgi.ebay.com/ebaymotors...i%3D1

[lino]

The fuel pump is in and the car feels like it has gained +200hp. What a difference! I belive the 2 most important parts I've replaced in my car were the thermostat and the fuel pump. There are no symptoms of any of the issues I've complained about at all.

I took the car out for a drive and I was amazed at the difference. I took off from a traffic light slowly to create some distance from the car in front of me and then nailed it, and the rear end fish-tailed left right left, this is going up a hill and with snow tires. I don't understand how I was driving the car before. I'm starting to really understand how this car is supposed to behave. I barely have to touch the accelerator now and I find that I'm always running out of road and constantly looking at the speedometer. I'm so used to pushing down so much on the accelerator to move slowly ahead and I'm not used to this new touchy pedal. I'm loving it though.

I'm sorry it took me so long to respond back. I've been going through a difficult time with a family related matter. I want to thank all you guys for you help and kindness. I'm so relieved that this problem is resolved.

I did run into a problem though. The spring on the floater of my sending unit was damaged during the installation, and so I'll have to replace it. Because of that, my fuel gauge never goes down to the Empty when I turn off the car, and it displays an inaccurate reading on the gauge. I'll warn anyone doing this job to take good care to be careful with the floater when you try to put the fuel pump back into the tank.

I wish I listened to Wes and Dennis and got a fuel pressure test done. I did go to get it done, but my mechanic's gauge was broken and I don't like going to my local dealer. Bottom line, getting a fuel pressure test is an absolute necessity in my books.

[Jesda]

Awesome! Another Q back on the road. Hopefully you finally get some reliable service out of it.

[maxnix]

So how did the original "new" fuel pump become bad?

[lino]

So how did the original "new" fuel pump become bad?

What do you mean by "new"?

I've sent my old pump, the original one that was in the car, to Keith for analysis. We have to wait for him now.