Help! 240 idle problems
#1
08-24-2012, 01:14 AM
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Help! 240 idle problems
So I've been fixing a 1982 240 ATX for a friend. Fixed a ton of brittle wiring, new radiator, inner tie rods, muffler, rear bumper, coolant and did a transmission fluid flush with a full case from NAPA. Car has been running perfect until I tried to start it this morning. It will start, but needs a heavy feathering of the throttle to stay going. It was driving and running fine before today. Now it has a pop, kinda like a light back-fire, and doesn't want to stay running. It has spark and air, and the fuel filter is new, I took it off to check for particles too. Nothing. The fuel pump relay is working, and I hear the pump in the tank at all times if the car is running.
Are there two fuel pumps (in tank and under the car) in an '82 like my '88 has? Where is the other pump? What is the fuel pressure supposed to be? I can't see or hear any vac leaks. This new pop sound has really got me stumped. What does that indicate? Any ideas appreciated. Thanks!
Are there two fuel pumps (in tank and under the car) in an '82 like my '88 has? Where is the other pump? What is the fuel pressure supposed to be? I can't see or hear any vac leaks. This new pop sound has really got me stumped. What does that indicate? Any ideas appreciated. Thanks!
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08-24-2012, 01:16 PM
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#3
08-24-2012, 05:48 PM
is an 82 K-Jet CIS (mechanical) or LH electronic injection ?
I don't know beans about the earlier cars, but if you've fixed a ton of bad wiring what are the odds you missed some?
LH fuel pressure should be 42-44PSI above manifold vacuum (treat manifold vacuum as a negative number, so -7psi vacuum reduces the 42 to 35psi)
I believe K-Jet fuel pressure is up around 65 PSI but I haven't ever worked on a K-Jet Volvo.
LH systems have dual fuel pumps, one in the tank, one under the car. I *think* K-Jet is similar (my 1984 VW CIS had dual pumps).
I don't know beans about the earlier cars, but if you've fixed a ton of bad wiring what are the odds you missed some?
LH fuel pressure should be 42-44PSI above manifold vacuum (treat manifold vacuum as a negative number, so -7psi vacuum reduces the 42 to 35psi)
I believe K-Jet fuel pressure is up around 65 PSI but I haven't ever worked on a K-Jet Volvo.
LH systems have dual fuel pumps, one in the tank, one under the car. I *think* K-Jet is similar (my 1984 VW CIS had dual pumps).
#4
08-24-2012, 09:20 PM
If yours is a k-jet system, try this web site:
K-Jet.org | Mechanical Fuel Injection Power!
Has some good info - mainly pdf copies of the green books from Volvo. There's not a lot of expertise on the k-jets here.
Good luck
K-Jet.org | Mechanical Fuel Injection Power!
Has some good info - mainly pdf copies of the green books from Volvo. There's not a lot of expertise on the k-jets here.
Good luck
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08-25-2012, 01:29 AM
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#6
08-25-2012, 11:50 AM
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I think I figured it out.
This is a VERY common problem in Volvos reaching the age of 15 years and older. Often the actual in-tank pump is NOT broken, but the RUBBER FUEL HOSE that goes from the pre-pump to the metal feed tube inside the tank decomposes and falls apart after many years of being submerged in fuel. When this hose ruptures, the in-tank pump can no longer push fuel out. The main pump under the car will try to make up the difference, but it can't keep up, especially when your tank is half full or less, when your fuel level is at or below that hose rupture.
A GOOD TEST: If the symptoms go away after filling the tank up, then this is your problem. Opening the top of the tank (in the trunk or cargo area) and replacing that small hose is the cure. A simple piece of 5/16 inch fuel injection hose about 3 inches long works fine. And replace those cheesy hose clamps with nice new ones while you're at it. You might be shocked to find out how many people have been advised by service technicians that they need new fuel pumps when only a short piece of fuel injection hose was needed.
A GOOD TEST: If the symptoms go away after filling the tank up, then this is your problem. Opening the top of the tank (in the trunk or cargo area) and replacing that small hose is the cure. A simple piece of 5/16 inch fuel injection hose about 3 inches long works fine. And replace those cheesy hose clamps with nice new ones while you're at it. You might be shocked to find out how many people have been advised by service technicians that they need new fuel pumps when only a short piece of fuel injection hose was needed.
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