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Possible fuel pump problem

T

TravisZ28

New member
Joined
Jun 18, 2021
Hi all, my question is, My 1986 244 DL starts and runs but when I try to rev the engine it starts to misfire or cut out when I get to "X" RPM or load. I have replaced the fuel filter under the car and the injectors and the vehicle was sitting for two years. Does this sound like symptoms of a bad in tank pump?
 
I have no idea how much fuel is in the tank, but, I did put 4.5 gallons of fresh fuel in on top of it. The previous owner stated that he though the tank was almost empty when he put the car in storage, but, who knows. I have been thinking about just filling the tank to see if bad fuel is the problem, but I don't want to fill the tank just to make the of of changing the in tank pump more difficult. Filling the tank would be the easiest thing to try first however. Also, can anyone point me in the direction of a wiring diagram for my 1986 244. I have a haynes manual and it only goes up to 1984.
 
84B23F said:
For some reason, Volvo does not want mods to post wiring diagrams:
"Under legal agreement with Volvo NA, MVS administrators have agreed not to post links or host content of copyrighted Volvo wiring diagrams."

Under the same legal agreement , users who are not admins are free to do so, and many report googling ?Volvo wiring diagrams? is fruitful
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.
 
TravisZ28 said:
I have no idea how much fuel is in the tank, but, I did put 4.5 gallons of fresh fuel in on top of it. The previous owner stated that he though the tank was almost empty when he put the car in storage, but, who knows. I have been thinking about just filling the tank to see if bad fuel is the problem, but I don't want to fill the tank just to make the of of changing the in tank pump more difficult. Filling the tank would be the easiest thing to try first however. Also, can anyone point me in the direction of a wiring diagram for my 1986 244. I have a haynes manual and it only goes up to 1984.
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What did the fuel gauge indicate ?

:-P
 
Otto Mattik said:
What did the fuel gauge indicate ?

:-P
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Empty, even after adding 4.5 gallons of fuel. I think I am gonna try filling the tank while I wait on the bung nut tool from IPD. I will update my post after filling the tank and let you guys know.
 
So, after filling the tank, the gauge shows 3/4 full. This misfire did not go away, and the tank appears to have had at least 5 gallons of old fuel before I put 10 gallons of new fuel into it. Dalek, thanks for the recommendation, I will check that out!
 
So.. an update...I put the fuel pressure tester back on the car. at idle with the vacuum hose hooked up to the regulator fuel pressure held rock steady at 29-ish psi. With the vacuum hose disconnected and plugged, fuel pressure rose to a rock steady 39-ish psi. This was through any and all misfiring. So...this would tell me that fuel pumps are fine...my misfire is coming from elsewhere. I would assume that my 10 gallons of known good gas would would trump whatever may have been in there previously. So...any other recommendations of what to check?
 
Have you looked at the spark plugs? You'll see what's going on in the cylinders. You can have a misfire from a bad injector as well as a vacuum leak. It can also be the dist cap rotor or plug wires causing the miss.
 
dl242gt said:
Have you looked at the spark plugs? You'll see what's going on in the cylinders. You can have a misfire from a bad injector as well as a vacuum leak. It can also be the dist cap rotor or plug wires causing the miss.
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I am gonna check the plugs as well as the cap and rotor next chance I get. I have decided I am also going to get an intake gasket and replace the sensors under the intake manifold as well. I have 4 new injectors in their already (I completely understand that this does not mean one might be bad). Vacuum leaks kind of worry me because I really don't have anything other than recent history on the vehicle and have no idea what previous owners may have done/not done to the car.
 
Bad gas can ruin spark plugs almost instantly. I've been down that road too many times. Plugs are cheap and the car is probably due for them anyway. Put in a new set and see what happens.
 
2manyturbos said:
Bad gas can ruin spark plugs almost instantly. I've been down that road too many times. Plugs are cheap and the car is probably due for them anyway. Put in a new set and see what happens.
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I understand what you are saying and wasn't sure about the bad gas deal...good to know. However, the plugs in it now are fairly new...been in there a month or two.
 
TravisZ28 said:
I am gonna check the plugs as well as the cap and rotor next chance I get. I have decided I am also going to get an intake gasket and replace the sensors under the intake manifold as well. I have 4 new injectors in their already (I completely understand that this does not mean one might be bad). Vacuum leaks kind of worry me because I really don't have anything other than recent history on the vehicle and have no idea what previous owners may have done/not done to the car.
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I ordered Viton o-rings on sale hoping to eliminate my injector vacuum issue. I was very careful, cleaned everything, etc.. and later found injector #4 has a vacuum leak in less than a year. You can spray carb cleaner or ether around the injectors to check for vacuum leaks.

Also don't underestimate the problems bad fuel can cause.

:nod:
 
Otto Mattik said:
I ordered Viton o-rings on sale hoping to eliminate my injector vacuum issue. I was very careful, cleaned everything, etc.. and later found injector #4 has a vacuum leak in less than a year. You can spray carb cleaner or ether around the injectors to check for vacuum leaks.

Also don't underestimate the problems bad fuel can cause.

:nod:
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As posted earlier, I put 10 gallons of new fuel in the tank on top of what ever may have been in there. Just checked and the plugs are not fouled out. I am not getting detonation which I would expect with bad gas, correct?
 
TravisZ28 said:
As posted earlier, I put 10 gallons of new fuel in the tank on top of what ever may have been in there. Just checked and the plugs are not fouled out. I am not getting detonation which I would expect with bad gas, correct?
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As far as detonation, you might try removing the fuel pump fuses(or relay) and see if you can get it to fire on known fuel, ether or similar. At least then you might be closer to a deduction.

I've had mixed to poor results adding fresh fuel to failed fuel, and usually ended up removing the fuel with an inexpensive syphon device.



;-)
 
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