Hi everyone I am a new member to the forum, I have a 1991 740 Volvo (non turbo) with 110,000+ on it. I cant get this car to start, it just cranks and wont start. It was running fine before I let it set for about a week. I have replaced the fuel pump, fuel filter and crank sensor. I am getting a spark and fuel to the engine and I have checked all vacuum lines and wires, Im stump. Any help will be appreciated and thank you.

 

Squirt some Starter Fluid into the intake. If it momentarily fires up you'll know it is a fuel problem; if not, then it's ignition...
Also:
I'd check the timing belt, make sure it's there and has not skipped teeth.
I'd make sure there aren't any intake leaks (between the air cleaner and the throttle body.

 

I think the belt has been replaced but I will check it anyway. I will try the starting fluid spray and check the breather assembly. Do you think it could be the computer? I ran the codes and got a crank sensor code. I also have no activity on the tach, before or after I changed the crank sensor. Thanks

 

Not likely to be the computer but not unheard of...

Is the crank sensor Volvo? Many problems these days with cheap NEW parts coming from who knows where--just because you changed it doesn't mean 100% guarantee that it's good. What was the old CPS doing? Did you replace it hunting the problem, or "just because"? If the car was OK before you changed it, obviously that's your problem.

 

I pulled a CPS code and there was no tach activity when cranking the engine. I parked it for about a week and came back into town and it wont start, It ran perfect before I parked it. O I forgot to say, I had some melted wires running to the O2 sensor that I fixed while I was searching for the starting problem, if that makes a difference?

 

Water in your fuel is always a possibility, and worth considering because it is easy to fix. A good slug of methylated spirits straight into the tank will soak it up with no ill effect on the engine.

 

So, the car ran OK with the new CPS? Then after sitting for a week, no start?
The O2 sensor should make no difference as far as starts are concerned.
What about the fuel pump?
No matter, squirt some start. fluid and you'll know if it's the fuel not getting to the right place.

 

The new CPS was after it wouldn't start, I thought it was the problem since I pulled a crank sensor code. When I get back in town I am going to see if I have power running to the injectors and yes I am going to try the starting fluid spray. I don't believe I have water in my gas, It ran good until it sit for a week. Fuel pump has been replaced and I am getting gas at the fuel filter and the fuel rail. Thanks again.

 

what about the suppression relay...or something like that....causes a no start....

Radio suppression relay .....can't remember the freaking name....

 

I'm going to see if there is power to the injectors so I can check them relays off the list. I believe they are on the right shock tower in the engine compartment and there is two of them. Thanks

 

Up date: I have movement on the top end of the engine, so the belt is good. I have power to the injectors so the radio suppression relays are good. I am going to the parts store to buy some starting fluid spray. I will keep you guys updated. What about the fuel pressure regulator? And why do I not have any tach activity still? Thanks guys

 

Ok, I sprayed starting fluid in the intake and it tried to start. I had a jumper wire in place of the fuel pump relay and had fuel pressure and wouldn't start, so I put the relay back in and checked the fuel pressure at the rail and I have fuel pressure for about 2-3 seconds and then nothing. I am stumped, I can put a test light on the fuel pump fuse and turn the key on and the test light lights up and then goes off after a couple of seconds. Still on the fuel pump fuse I can crank it and the test light stays on as long as I crank it. Could it be the computer? Please help I am out of ideas. Thanks

 

I replaced the computer and I have the same problem. Please help

 

Super Moderator Pierce, Do you have any suggestions? Why wont this thing turn over when I jump the fuel pump relay?

 

Can anybody help? I am leaving town again Monday.

 

This might sound like a stupid question but how much gas is needed in the fuel tank to start these cars? I have a little less than a 1/4 of a tank if the gauge is correct. If I recall, the new fuel pump I installed was a little shorter than the one that was removed.

 

Wires to the crank sensor sound suspect. Also, is there a certain air gap required for them. I don't know if they can be adjusted. I've worked mostly with the older hall effect sensors and not the reluctor flywheel pick-up as your car has.

I would think 1/4 tank o' gas would be fine.

When my hall effect sensor failed, sometimes I would get a weak lame spark. But it would never start. I'd make sure that the leads to the CPS are not crossed and are continuous.

 

The CPS on these is a direct bolt in, no adjustment needed. When I jump the relay I have gas to the rail but it wont start. What would cause this problem all at once? It was running fine prior to it not starting.

 

Update: No tach. activity when cranking the engine, No constant fuel pressure at the rail and I do have injector pulse. I checked the pulse with a noid light. I have replaced the cap and rotor since it didn't look that great. Can anyone help.

 

YOUR CRANK SENSOR....DISCONNECT AND CLEAN THE CONNECTIONS WITH CRC ELECTRICAL CONNECTION CLEANER...HELL CLEAN ALL THE CONNECTIONS....COIL, BATTERY TERMINALS...ETC...DO YOU HAVE YOUR OLD CPS HANDY? you replaced it as maintenance or you had previous codes indicating it was faulty?


CHECK LIST:

ENGINE FAILS TO START

1: Discharged battery
2: Loose battery connections
3: Loose or broken ignition leads
4: Moisture on spark plugs, distributor cap, or HT leads
5: Incorrect spark plug gap
6: Cracked distributor cap or rotor
7: Other ignition system fault
8: Dirt or water in fuel
9: Empty fuel tank
10: Faulty fuel pump
11: Other fuel system faul: eg FPR, fuse
12: Faulty starter motor
13: Low cylinder compression...not likely since you were driving it prior