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-   -   Transfer pump shot?? (https://volvoforums.com/forum/volvo-240-740-940-12/transfer-pump-shot-41017/)

iatotofts 04-21-2010 07:41 PM

Transfer pump shot??
 
So I got the car all legalized and driveable.. And now I find that it is really hard to start when the engine is warm.. And also it will "lurch" forward and shutter on deceleration (I guess thats vapor lock?). And it will stall sometimes after depressing the clutch, as well as Dropping RPM's FAST between gear shifts..
I was reading in my book about the fuel system, and it says that "Some of the most common symptoms of a faulty in-tank fuel pump are: hot starting problems (I've got that), reduced top speed (I'm not sure about this one), vapor lock and engine hesitation (i'm guessing this is the lurching I was talking about) and loud noise from the fuel pump (overworked) (MY fuel pump is really loud). If the transfer pump is not working, the engine usually starts and runs using only the main fuel pump.
Come to think of it, aren't you supposed to be able to hear the transfer pump essentially prime the system for a second or two before you crank the motor? Because I have yet to have ever heard that. I only hear what I guess is the main pump and thats ONLY when the motor is rotating..
And the engine while idling will start to surge up and down in the RPM band as well..

Do you all think i might have a bad transfer pump as well? I'd like to get your opinions too.. Just to kind of ease my troubled mind...

swiftjustice44 04-21-2010 10:19 PM

OK...the intank pump is a lift pump, doesn't produce much pressure...just hoists it up out of the tank for the under car main pump to get hold of. The under car, or main, or in-line pump, is the one that really cranks the pressure. The car will run without the lift pump BUT usually the main pump will be noisy as it is working harder than it cares to.
Some cars you can hear the pumps...others you can't. I've had some success using a piece of vacuum hose as a stethoscope, sticking it into the gas filler neck while someone turns the key to the run position. You may hear the intank pump this way.
The best test of an in tank lift pump is also the most dangerous. I hesitate to even mention it as I wouldn't want anyone setting fire to themselves. If one disconnects the gas line coming from the tank where it connects to the main fuel pump and places the loose hose in a container...turning the key on for just a second should result in a healthy stream of gasoline...a surprisingly healthy stream! No gas? Pump no bueno! Be sure to check fuses.

iatotofts 04-22-2010 11:26 AM

thanks i'll have to check it out.. I'm gonna check fuses and also make sure power is actually gettin to the pump itself.. Do you by any chance know what the effect of Vapor lock is? And also why a failed Transfer pump would make it harder to start when the motor is hot as opposed to a cold start?

bubba240 04-22-2010 01:07 PM

What year is the car? One thing you can do is place a jumper wire (paper clip, etc) between the left sides of fuses 4 and 6, both pumps should run constantly with the key off ... Which will make it easier to hear them. In this condition place our ear to the gas fill tube with the cap off, or remove the inspection plate in the trunk. My in-tank pump is fairly high pitched, sound wise.

Also clean/inspect fuse 4.

iatotofts 04-22-2010 10:05 PM

It's an '88. Yea I know i have jumped them before but at the time I didn't know I had two pumps.. I'll give that a try this weekend and see how it faires... And then post a reply!


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