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Still fighting this hesitation demon on an 89 240 wagon. 113K on clock, recently (last 3 months) in service after sitting for an extended period. Attempts to get maintenance up to snuff, I've replace the in-tank fuel pump twice now which does not impact symptons. New in-tank pump sock. New main pump, fuel filter (Bosch), and poor electrical ends on main fuel pump removed and spliced in new wire. Brand new marine grade 25amp fuse and holder under hood for fuel injection. Cleaned all connections on black connector on driver's inner fender that leads to battery. Above average correct battery. Posts cleaned. All fuse holders on interior cleaned with wire brush and all fuses replaced with copper fuses. I do not know the fuel pressure while driving. Have had some vacuum hose deterioration which reduced problems when a zip tie was applied to the vacuum nipple at intake manifold. Two fuel injection relays interchanged and no changes. Symptoms are an unexpected loss of power and if you feather the pedal, seems to have no power. Sometimes will just catch and go on, but most of the time all it takes is to turn the car off, sit for about 5 mins and start and go, mostly with no more problems. Does seem like it may be related to a less than 1/2 full tank, but inspection of the little rubber hose on the in-tank pump appears intact and without deformity. I'm beginning to wonder about the fuel pressure regulator whether it's a mecanical issue or one of vacuum. Air filter is new (Mann). New cap and rotor, wires and plugs (NGK), new timing belt and front seals (Volvo brand). Got an oil leak I can't figure out and the A/C needs charged, but rides very nicely on the new Michelins.
Thanks board memebers!
JBeechcraft
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The relation to less than 1/2 a tank of gas sure points toward a problem in the tank. Has the fuel gauge sender assembly ever been replaced? Sometimes the replacement assemblies come with goofed up wiring. For example, the last one I installed had the polarity for the fuel pump reversed at the pump, and had the connections for the fuel pump and fuel gauge switched around at the harness connector. Can you hear the in-tank pump running?
Try closely examining the wiring from the pump to the harness connector and make sure everything is right.
I suppose that, even if the pump is running, it might be running backward.
--
1966 122s, 1968 142s, 1969 144s, 1979 245dl, 1989 244gl
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Here's another idea for a test. Disconnect the main pump power connector at the pump so it won't run. Disconnect the intake hose to the main pump from the in-tank pump and put it in a container to catch the gas. Jump the fuel pump relay to engage the pump. If the tank-pump runs and gas comes out of the hose, all is right. If it runs but no gas comes out of the hose, the polarity is reversed somewhere. If it doesn't run, the pump either isn't getting power, or it is bad.
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1966 122s, 1968 142s, 1969 144s, 1979 245dl, 1989 244gl
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Hi,
Can't remember exactly, but does your 89 have the OBD code box in the engine compartment? If so, have you checked for codes?
Travis
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That's where it all starts -- CPS times ignition, which propagates CPS pulses to Fuel system.
CPS wiring is known to go bad with age, and 1989 was the first CPS year for the 240.
--
Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.
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Bruce!
Thank you for your efforts as well. I think you are on to something. The cps did not even cross my mind. I now wonder if the rear main seal leak is contributing to the CPS in two ways; A) degrading the insulation of the wires if motor oil in on them; B) directly interferring with the CPS signal by way of oil on the magnetic tip. In my efforts to get this car utterly reliable and as part of my preventative maintenance, I will first hit the bone yard tomorrow and see if I can scavenge one from a donor car just to see if that is the problem. Meanwhile, I will also order a factory original to replace. I shall report back. Drove the car in the near summer heat today, and not a hint of the hesitation situation. I no longer feel like I can safely or predictably get from point A to point B and postpone errands out of a concern for getting stuck.
Thanks again for the tip Bruce, I think this is the solution!
Sincerely,
JBeechcraft
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'Falling flat then picking up.' Hmmm almost sounds like it's going into Limp mode.
Clean connections on AMM.
While you are playing.. Is the Thermostat in the Air Filter box functioning properly? Or is the Metal hose from Exhaust manifold to Air box disconnected?
If this Metal hose is intact as it should be. Take it off the exhaust manifold and see if symptoms change
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/
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Thanks for your thoughts Tony!
I will check the connections onf the AMM. I have not done that yet. As to the thermostat in the air box, here in hot southern Florida, we pretty much disconnect them routinely. There is no hose going to the exhaust, in fact, all the associated tin has been removed and placed in a storage box. Just straight factory headers and factory exhaust throughout.
Thanks again!
JBeechcraft
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I was hoping you were going to tell me that the Plumbing to the air box was eliminated. It sure sounds like the car will drop down into Limp home Mode and that's the loss of power. With the AMM being safe from very hot air then I have to think you have an intermittent connection at the AMM connector.
I'm just taking a shot here, sounds like you 've taken all the other avenues.
Being you are in Fla, I wouldn't suspect green nasty contacts but look closely at the pins in the connector. See if any are spread out too far causing them not to squeeze the contacts on the AMM
--
'75 Jeep CJ5 345Hp ChevyPwrd, two motorcycles, '85 Pickup: The '89 Volvo is the newest vehicle I own. it wasn't Volvos safety , it was Longevity that sold me http://home.lyse.net/brox/TonyPage4.html http://cleanflametrap.com/tony/
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Sounds something like what *my '89 wagon is doing, though mine has been just flat dying lately, then not starting for awhile. Twice now, I'll jump the #4 and #6 fuses, and the main fuel pump doesn't run. Then after awhile it starts, or the pump runs when fuses are jumped.
I just found degraded insulation on the wires at the fuel pump plugs, and the plugs were really hard to get out. We'll see if that was the problem... Did you double-check the electrical connections to the pump, put dielectric grease or anything in the plugs? Are they water/dirt-proof? I'm trying to imagine how to get mine to be that way when I put it back together...
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Thanks for taking the time to contribute! I appreciate the suggestion. It just so happens to be one of the things I've recently done. I found a delicious new Bosch main fuel pump in the bone yard and changed it along with the fuel filter. I immediately noticed that the wiring was in very poor condition and spliced in new ends. They are will get a final once over and thorough sealing soon, but I believe that I'm covered on that one.
Thanks!
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Well darnit, that wasn't my problem, either. I was hoping it was just a dirty plug...
Since the main fuel pump only makes a very quiet splutter right now -- though it may start buzzing loudly/working fine again the next time -- I guess I have go ahead and buy a new Bosch pump. I read that they may be made in China, or any number of other places, and may not really be any good anymore...
Sorry, all this rambling helps me figure out how it all works...
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I just bought a new Bosch main pump a about 3-4 months ago to put on the shelf-it's made in Germany-pick one up on Ebay as they seem to be the cheapest there.
Travis
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