91 940 Turbo Wagon 247k. Well now it just died and is sitting at a gas station. Drove fine then all the sudden started running really rough. Nursed it over and it would idle but did not want to rev. Sounded like it was on 3 cylinders with a hole in the exhaust. Then it was idling around 1500-1800 all by itself (guessing the compute was trying to compensate) but would not rev. Then it went to barely running at all and died. Now it wont start at all. When it was still running I unpluged the MAF and it idled up and then went back down and still would not rev. Put it back on. Now it just cranks and cranks but wont do anything. Not sure where to start!

 

Well got it started. Cranked and cranked no fire. So went under the hood and started moving wires. Moved the 2 spades on the coil, unpluged the plug wire going to it and put it back on. Next I followed all the wires around and wiggled them all. Is it the crank sensor or rpm sensor(single wire on something left front of motor under turbo and then to the front). wiggled a bunch of wires. Cranked and it sputtered. Did that 4-5 times and it would idle but real low. Pulled out my phone to take a video and by the time i got it ready, the car idled on up and was fine. I reved it a few times and jumped in and drive it home. It smoked for a minute but everytime I have gotten it to start after it would not it has done that. Only lasted a minute. Drove fine home 2 miles tryed to act up once but smoothed out.
Wonderwhat the right wiggle was and has this been my whole problem the whole time?

 

bump bump

 

thought maybe crank sensor now nothing!!!! no start at all!

 

The crank position sensor would be my first guess. how do the wires look on it?

 

old wires looked bad, changed sensor still nothing. Think I may have tracked t down to the radio supression relay, swappped it with fan relay and it tried to start then nothing. Swapped them back and the fan is not running so both relays are bad. Going on a hunt and yes the fan worked before

 

well its me again. radio suppression relay did not fix it. Fan runs again but nothing.

 

ok folks got some good hard info. have good spark, good injectorpulse, good ignition. External pump running, internal pump running. radi supp relay was bad. Everything is right except I am gettin no fuel to the rail. Pulled intank pump to make sure it it was pumping, put in pan of gas it pumps good. External pump is coming on but I took the line off and it does not put anything out. You tqke the line off the main pump thqt goes to filter and I get nothing just alot of air. OK so now I have everything except fuel, i am thinking the internal pump is not getting low enough now to puck up fuel, maybe the sending unit is not fitting down in exactly and not laying in the gas. tomorrow gonna fill it up by way of gas can and see if i get fuel then. so everything is fine execpt the fuel

 

Taking a shot in the dark here, but could it be the fuel pressure regulator? Or the fuel pump relay?

 

thanks for responding eskimo. Relay is good, have not replaced regulator but at the moment the intank pump is not picking up the fuel. I unhooked the fuel line to the main pump and the internal is not puttting any out. Got about a .25 tank of gas but it is not gettng down there to it forsome reason. Pulled intank and submerged it in a pan oof gas and it pulls good. So more gas it is for now.

 

Go to www.stepbystepvolvo.com for free no-start guide to 740/940. Sounds like it is your main fuel pump.

 

Main pump is good, there is no fuel making it to the pump from the intank one.

 

IT LIVES!!!!!! The mass air meter is bad though. Idles rough and wont stay running with out giving it gas. Unplug it and it idles great but if you gas it, it dies.

 

Replaced AMM and still runs the same.

 

Sorry to everyone who quit looking at my posts. The car is now fixed. After everything the positive wire on the fuel pump had broken away from the clip and was not making direct contact. Replacedd AMM and no luck but it would idle ok unplugged. Fixed fuel pump wire, plugged in AMM and the rest is history. Thanks to all who gaveme advice on this and the former thread!!!!

 

Forgive me if I have this thread confused with another.

Is this related to the problem with the fuel tank being loaded 1/2 or less and the vehicle failing to run? If so, why do you suppose a bad positive wire intermediate connection on the fuel pump could be the culprit. I'm not challenging your solution, I'm just trying to resolve in my head the physics of the problem and the solution. Was the failed connection at the in tank fuel pump? I'm not too sure why I ask that question.

regards

- rev -

 

Sorry, I should have put my mind in gear before putting my fingers in motion.

 

Its all good. you are correct this is related to the 1/2 tank thread. I really do not know if that was fixed or not. I replaced the intank pump and sock. It worked great outside the car in a pan. Gas guage is working now also. Gonna have to see when it gets down below 1/2 again. So yes the car is fixed as in it is not broken down anymore but the 1/2 tank deal is a mistery still.

 

Well got below 1/2 tank and it ran out of gas, made it home this time though. So I have an inspection camera on a 40" line w/ lcd screen. Unfortunatly it was too rigid and would not make the turns through the sending unit. So I pulled it all again. Laid unit out how it was in the the tank and it dawned on me!!. THE SOCK WAS POINTING UP!!!. So this direction was the only way I could ever get it to lay before. This time put it back in, moved it sideways and it went right in. Gas guage is right and I am not running out of gas at 1/2 tank anymore. Just figure I would say this.

The main fuel line and the return line go on the bottom right when in the correct position not straight up.