Regina 740 dies on right turns Topic is solved

[jpgurley]

I am stumped. I picked up this nice clean 91 740 wagon that had not run in years. After replacing the high pressure in tank fuel pump, the fuel filter, flushing out the tank and all the usual tune up stuff the car runs great! Except for one problem. If it is below 1/2 tank it stalls on a right turn and often catches back up without hitting the starter (It is an automatic).

Here is what I have tried so far:
I removed the fuel muffler from the in tank unit and put in a straight line.
I replaced the entire in tank unit with a "rebuilt" one that has a Bosch high output pump on it.
Since then I have experienced the skipping at highway speed in a right hand curve with 3/4 tank of gas!
If I didn't know better I would think that it has a "rollover cut out relay" but I don't think it does.
My tests so far have indicated that the ignition is steady (primary and secondary)
The voltage and ground at the injector acts like it is in a deceleration mode but they do not loose all voltage.
I know that Regina models are different in a few ways, but I am getting very confused by this problem.
Before I pull the fuel pump assembly for the 5th time any ideas of what to look for?
I'm thinking that perhaps the return fuel is causing a fuel starvation issue but the baffles in the tank should prevent something like this. I think.
Look forward to some suggestions.
My wife is afraid to drive it.
Making left turns in North Carolina.
Jon

[RickHaleParker]

that had not run in years.

Chafed wires from rodents chewing on the wires.

[jpgurley]

Well it seems like that would be visible somewhere. I've seen plenty of Bosch plug wires eaten up before by rodents. When I was a Volvo Service Manager (in the 80's) we did a lot of wiring harness replacement due to degrading wire coatings. This one looks fine. That would not explain why a full tank keeps it running fine until the fuel level goes down. Thanks for the suggestion though.

Did the safety minded swedes have some kind of roll over cut off? Ford did back then with a resettable relay in the trunk.


It really feels like the car dies when the fuel is sloshed toward the driver's side which is where the fuel pump assembly is in the tank. ???

Thanks,
Jon

[RickHaleParker]

Did the safety minded swedes have some kind of roll over cut off?

For the 1984 - 1992 740 it is Volvo part number 1255422.

[jpgurley]

Thanks for answering my rollover valve question.
It appears as if this is a device to prevent fuel from leaking out of the vent/EVAP system when the car is not upright.
Unlike Ford (and others) who electrically turn off the fuel pump I can see that this system could not be producing my dying on right turns problem.
So the mystery continues.
I think my next examination is going to be a clear fuel line on the return to see if any bubbles appear in the fuel circuit when the dying happens. I'm still working on the premise that something is happening in the tank when I turn.
Glad you have access to the data.
Now have you got any illustrations of the baffles in the tank?
Thanks again,
Jon

[RickHaleParker]

Now have you got any illustrations of the baffles in the tank?

No illustrations of the baffles or tank construction ... but: If you look at the picture above your see a reference to a "Equalizing pipe" . The screen shot is from the parts catalog under "Balancing system for fuel tanks" ....

[jpgurley]

That does look interesting!

If I am seeing the illustration correctly, that is what I would call the fuel filler pipe vent.
The line that is attached to the Fuel Pump assembly (at the very top) that is about 1/2" id and vents vapors back to the filler pipe right downstream from the gas cap. That parts illustration only shows where it goes into the bulkhead and not where it ends on the tank, but I have removed and reattached it each time I have gone into the tank.
I will examine more closely that when I take it apart next time.

I am curious about where the fuel pump gets it's ground.
Do you have a schematic of that location?
Thanks again for your input.

Jon

[RickHaleParker]

I am curious about where the fuel pump gets it's ground.
Do you have a schematic of that location?

When it stalls, does the engine shut down abruptly like somebody turned the key off or does it wind down over a period of a few seconds?

Have you tried raising the right side then left side of the car to see if it stalls? If it does you would have the condition right there in your work space where you could trouble shoot.

The 1989 shows fuel pump grounded in Electrical Distribution Panel. Electrical distribution panel is the lower half of the fuse panel. The fuse panel is attached to the top of it. One could say it is a common ground buss inside the fuse panel. -31 below

[BlackBart]

This might be a left field idea....

Is it possible that the new pump assembly stack is a different height from stock and the pickup is not sitting flat and tight to the tank floor?

[jpgurley]

Thanks for the input guys.

I have not tried to jack the car up on the right to tip the fuel but that's a good idea.

The car acts like you have turned off the switch when making the right turn, but the tach stays steady and I even had a timing light taped to the windshield and the secondary continues to spark when this dying happens.

Yesterday I tried something. . . I put a clear hose on the return line and at idle there are bubbles in the fuel.

At this point my theory is that the fuel pickup sock is sucking in agitated fuel with some air in it and when the turn is made the pump "cavitates" with air.

Not sure, but I am leaning toward the fuel return in the tank being so forceful that it is putting bubbles in the fuel.

In response to the new vs original assembly I did take pictures of both side by side and they seem identical.

I have a full tank now so I will pump out 5 gallons and then take it apart "AGAIN" (spoken in Forrest Gump's voice).

Thanks for all the suggestions so far.

Jon