Major Ledfoot
Hoping for some words of wisdom about this issue.
I've just bought an 87 740T wagon with LH 2.2. and a B230F. It runs rough and lean under load when the factory fuel pressure regulator is connected. The guy I bought the car from, lent me an aftermarket fuel pressure regulator (which I have to return to him) just so I could get the car home.
When the standard FPR is bypassed so that the aftermarket FPR is hooked up to the fuel return line, the car runs acceptably, but a bit rich.
Now that I've gotten the car home, I've swapped out the original FPR (which we suspected was faulty) with a spare from a B234F which has the same part #, and removed the aftermarket FPR from the return line, thus putting it back to what should be factory spec.... and the original problem has returned!
Unless both of the factory-type Bosch FPRs are faulty, there has to be another problem. The MAF / AMM has been swapped, and it's not the issue (with the AMM disconnected, it runs even worse).
Any advice and guidance as to the finding the culprit will be gratefully accepted.
nickm
Have you set the base Idle. You can use a 12volt LED
Major Ledfoot
Nope, the base idle hasn't been set. It idles fine - the problem appears only under load... when the factory FPR is hooked back up as normal, and the jury-rigged FPR is removed.
After some tinkering today, I noticed the main fuel pump (under the front seats) is making a lot of noise (compared to the 16V car, whose fuel pump is a lot quieter). I pulled fuse #11 for the in-tank pump, and the main pump whining changes a little, but not much. Does this point to the FPR, the in-tank pump, the main pump, or none of these?
Vee_Que
The in tank pump failing is most noticeable with low fuel. I would reset the idle then amm with the guide from brickboard.
nickm
That could be more your problem. But check your fuel pressure.
The AMM can be adjusted you need to to remove the little plug in it to expose a screw. I effects the running.
https://brickboard.com/FAQ/700-900/EngineFuelinjection.htm#SettingBaseIdle you don't need the resistors if you use a 12volt led.
Major Ledfoot
Thank you gents - when daylight returns, I'll give this a shot. I didn't know before that the base idle setting could affect the whole operating range.
DCW242
If it's any help I did a full pressure in tank pump conversion on my Dad's '89 LH2.2 745T. Using a Bosch pump from an 850. It was pretty easy to do, I have the same set up on my '87 240. It works really well.
Vee_Que
In tank only pump is a silly thing to do vs keeping the giant Bosch 044 pump under the car on a turbo. Its literally a waste of effort.
DCW242
Not really. Newer cars use that system for a reason. It runs cooler, it's quieter. it uses a lot less power then two pumps, so less load on the fuel pump relay. and flows just as well.
Major Ledfoot
Thanks Duncan, but I'll keep the two-pump system. Other gadgets I've owned (specifically VN / VP Commodores) have had a single high pressure pump in the tank, and I've been less than pleased with the results. They really should have had a lift pump and a pressure pump to get the last 15 litres out of an 80 litre tank without surge, when the car is on a steep uphill climb.
Vee_Que
Yep. They fail and you're left stranded. Every performance car uses an external pump as an upgrade. Volvo just left then external stock for maintenance. Still ac waste of money and time unless the pumps were free. And the noise issue? Really? You don't hear them that well with the engine running, and the current draw, well you had to fit a 100a alternator to your 240, so at least it can power it, so that's a bs excuse too. Literally a waste of time!
Vee_Que
And proof on that little in tank fuel pump that gets upgraded on any turbo fwd volvo straight away flowing better than a lift and external pump that doesn't get touched until the car makes A LOT more power than a fwd would need its pump replaced at!
Vee_Que
The fact its running lean under load and a second in line regulator fixes it, means it has nothing to do with fuel flow... As your regulating regulated fuel. Blocked filter maybe? But amm issues are rich running..
Major Ledfoot
It's not running rich, so it cannot hurt to get a new fuel filter. I'll remove and inspect the in-tank pump too. I guess the second FPR must have been acting as a restriction in the return line and was bumping up the pressure to the fuel rail that way.
Vee_Que
Seems really odd. All the external pumps I've had fail just stop powering the car until I tap it and keep going till it gets replaced. But it could be. What was the aftermarket unit set to?
Major Ledfoot
No idea what the actual setting was on the external FPR,... The PO adjusted the thing until the car was running just a wee bit rich. He had a portable exhaust probe, which could give an estimate of AFR, and set it up to err on the safe side and keep it rich. But run it did.
Many moons ago, I had a VN Commodore (in-tank) fuel pump go intermittent low pressure - it would work okay for a while and then drop. Wasn't temperature related, it must have been on the edge of failure.
nickm
Have you verified the fuel pressure?
Major Ledfoot
Not sure if the PO did. Since I don't have a fuel pressure gauge, I'll have to buy one so I can verify it.
nickm
You could rig something up with a tyre pressure gauge.
Anthony
Coming in very late on this,
Did you fit a FPR from a turbo model, rather than a std B230F as they are very different spec.
You will run terrible lean on a std Fuel Pr Reg and risk melting pistons under boost.
I can explain further if needed.