Fuel Problems still...

zcobramike · Post by **zcobramike** » 05 Aug 2006, 12:48

Well; I started off knowing I had a dead fuelpump. I replaced it. Nothing. Then took off fuelrail and I re-tried it. Guess what...no gas. The fuelpump does not run at all. Someone told me the car may have a shutoff rollover sensor but they do not know for sure or where it is located. Also both fuse and relay are good. What about cutting the elect.lines and jumping it direct? -Any other sugestions? thanks, Mike

Post by **billofdurham** » 05 Aug 2006, 15:33

From earlier posts I understood that you had replaced the in-tank pump but could not locate the main fuel pump. Have you found the main pump yet? Your car does have two pumps, so which one is not running?

Also, you state that the fuse and relay are both OK. Which fuse did you check? There are two fuses for the fuel pumps - #1 - 25 amp for the main fuel pump and the fuel injection system and #11 - 15 amp for the in-tank pump and the heated Lambda-sond.

What about cutting the elect.lines and jumping it direct?

If you are going to jump the pump direct I would not advise cutting the cables. It would be better to run a feed from the positive side of the battery to the positive terminal on the pump - but do not connect it to the pump, just touch the terminal to see if it works.

There will be a rollover cutoff built in to the system but they only operate in a rollover and I have not heard of a failure of this part. I suppose, if your luck is like mine, you could have the first. I am researching the location of the cutoff and will let you know if I find it.

Bill.

740fromhell · Post by **740fromhell** » 06 Aug 2006, 04:08

are you getting any spark?

if not then you have a problem with the ignition system, which is a major pain in the butt on these cars. let me know if you get spark and if you dont then i can run you through a step by step diagnostic to determine what component in the ign system is bad.

cosmiclobster · Post by **cosmiclobster** » 06 Aug 2006, 18:29

I still didn't see any posting of which Volvo you have.
If you have the fuel rail removed and you crank the engine, you should get fuel squirting out.
Leave the fuel rail off, remove at least one fuel injector from the rail and power up both pumps for a complete test.
As for the roll over circuit, I can only speak for the 740 - when the car gets in a crash, there isn't a "rollover" circuit per se - there is a circuit that looks for timing pulses from the ignition circuit. These are the same pulses that power the speedo. These pulses go to the fuel relay and the fuel relay turns on. If the car crashes and the engine stops, the fuel relay shuts off and stops more fuel from being pumped out.
How did you test the relay?
Put a voltmeter on each of the pink wires that go to the fuel pumps (one at a time) and crank the engine. If there is voltage when you crank, the relay is good. If not, that is your problem.

Hope this helps

MO-T5 · Post by **MO-T5** » 07 Aug 2006, 07:01

You just answered my question for a 98 V70. You only get voltage at the fuel pump during start-up and when it is running. Is 10.91 volts OK to run the pump?

cosmiclobster · Post by **cosmiclobster** » 07 Aug 2006, 18:14

MO-T5 wrote:You just answered my question for a 98 V70. You only get voltage at the fuel pump during start-up and when it is running. Is 10.91 volts OK to run the pump?

You are correct. If you put the ignition key in the run position when the engine is stopped, the fuel pumps will not be powered up.

10.91 is a little low but it should run the pump fine. I'm guessing that you got this reading while you were cranking the engine? With the engine off and all electrical things off you should get a reading of at least 12.6 volts. With the engine started, that voltage should jump to between 13.2 and 13.8 volts.

MO-T5 · Post by **MO-T5** » 08 Aug 2006, 07:25

Yeah, i pretty sure my check valve is bad because sometimes it takes 5 seconds or so to start and it has pitiful resting pressure at the rail. Someone at another forum told me that with the key on I should get voltage, and that pointed to a ignition switch failure or something else. I'm just in denial about having to spend 300 bucks on a new pump. Thanks for the info.