Alright, I will explain this as best I can. My understanding of the problem is fairly limited.

Normally, When you turn the key to the run position, we hear a slight 'wurl' sound. My car doesnt do that. It doesnt even start. UNLESS.



That red wire, is struck against the FOURTH fuse down. The sound is heard, and the car will start in less then a second. The wire doesnt require constant contact, only 2 seconds or less, and sometimes not at all if you shut the car off, and start it again. After that the car will do everything normally.

The car was bought like this, and the owner did'nt have much clue to the problem either. I'm unsure of where to start.

Any help is appriciated.

 

Where is that red wire connected to? It looks like it is coming from the sixth fuse down, which is the main pump fuse. The fuse you are jumping is the transfer pump. What I know, is that if you jump the left contact of the main pump fuse to the right side of the transfer pump fuse, you will give the transfer pump power. If you connect it to the left side of the transfer pump fuse, you will power the main pump. So depending on where that red wire is coming from, it should either be giving power to the transfer pump (not likely as you said you can hear the pump whirl and a 240 can start without a transfer pump) or it is giving power to both. I think both. Strange it can run after that without the red wire stuck to it, tells me the fuse is probably just corroded and needs a little assistance getting electricity to flow through it.

 

this may be out in left field but I was having a similar problem and i spent weeks trying figure out my problem. finally i actually pulled the fuse out only to find the ends of the fuse were burned up. when i looked at the fuse it appeared to be intact.

 

Burn Stains is right about the 240 fuses causing electrical problems. To get rid of mine I pulled the negative side of the battery, removed all the fuses and with a small wire brush cleaned the all the contacts. There was all this white oxide forming. Pretty sure my elusive windshield leak is a player there. I replaced all the fuses with copper types (similar type metals). That has worked ever since.

It sounds like you may have a fuel pump relay problem. It is located above the passenger side footwell. It is white and should be mounted on a rail. These are known to give problems. The fuel pump relay gets its voltage from a 25 amp fuse, that comes off the battery, another source of "leave you stranded somewhere" syndrome. I checked mine awhile back and the fuse fell out of the holder, the holder was shot and fuse showed signs of arcing. I replaced it with a waterproof marine type fuse holder and new fuse.

I hope this helps.

 

Thanks for the input guys. Its been raining very hard lately, delaying my progress on the car ( I dont have a garage ) So I've been hesitant to start pulling things apart.

I have already replaced a few fuses causing lights and wipers to malfunction. I'll look into it tommorow.

I really appriciate it. I'll post more information when I have it

 

mercedes used these ssame crappy fuses, and on a few forums the benz-heads recommend just automatically changing ALL fuses if they are 10 years old, and solving all soorts of random problems.

that said, there's a relay that controls the fuel pumps, if that relay is malfunctioning, neither pump fires. jumping a red 'hot' wire to the fuse you describe will power the pumps in spite of the relay. on the later 240s (say, mid 80s and later), its a double-wide relay where the other half controls the fuel injection controller. anyways, this relay is behind the glovebox.

 

Okay so I ran down my list of troubleshoots. Of course now its pissing rain, again. Halting all work to the car. :-(

Fuses. While theyre clearly quite old, they all still function, including number 4. I did however replace it with a new fuse, and the problem was not corrected.
25 amp fuse for Relay. - I found this fuse when I bought the car, and was unsure of what it did, as it was caked in oil. It none the less seems to function.
Relay. Found that. It doesnt appear damaged. I've ordered another from IPD, and we will see if that corrects my problem.

It really doesnt bother me but, it's something thats broken, and I feel compelled to fix.

Thanks for the input guys, Really helped me out.

 

hmmm, you know what else it could be, it might be the one way valve after the main fuel pump... when you turn the key on, the pumps are supposed to energize for about a second to build fuel pressure then shut off because the engine isn't turning. when the car starts and is turning over, then the fuel pumps are turned back on and left on. if that one way valve wasn't holding pressure, there wouldn't be any fuel pressure when you were cranking the car over and it would be very hard to start. jumping the pumps with that red wire would circumvent this.

 

Very knowledgeable guy. I'll add it to the list of things to do, Right now, I'm stuck with doing bodywork day by day.

Thanks again

 

The benefit of this situation is that your problem acts like a kill switch in which no one will be able to make a clean getaway in your Volvo.
What are the reactions of passengers in the car when you have to do this all the time? Have you told them it was the latest, Swedish anti-theft deterrent of the time...

 

heh. my brother years ago had a heavily hotrodded nissan/datsun 240Z (the original). the fuel pump was connected via a switch under the drivers seat. if you didn't turn it on, the car would start (carbs, dontcha know), and go about 100 feet before stalling. this car was loud enough to wake the dead, and he in fact caught a thief exactly this way. oh, the driver door was tricky to open from the inside, hahaha, so the thief was trapped.