Just picked up a 91 Volvo 740 NA Wagon with Regina. Totally didn't need another car but having a 940 Wagon along with a complete parts car for it, I couldn't resist. When I bought it, car had no exhaust and ran horribly. Since taking ownership I have replaced the exhaust, O2 sensor, AMM, plugs, wires, air filters, cap, and cleaned the TB & replaced gasket. Also fixed a few vac leaks around intake

The car ran great for the first day after work was completed. Now several days later, under load it feels like fuel is cutting out around 3500k RPMs. If I mash the petal, it will just sputter and struggle to accelerate. If I let off the gas and car upshifts, I can accelerate normally again. I was planning on checking fuel pressure but I noticed the 740 fuel rail doesn't have a pressure port like my 940. Is there an easy way to check fuel pressure on these short of installing my spare 940 fuel rail?

Any other ideas on what could be causing this? I'm getting no codes and I've already done a compression test on engine which came back around 180 psi across all four cylinders. Car had been sitting for about two years when I purchased it. Had a 1/4 tank of old gas so I filled it with premium and added octane booster. If there is anything worth swapping over I have a a parts car that ran great at my disposal. Thanks in advance!

 

Some regina cars have a fuel pressure test point near the fuel filter, without it you place a gauge inline where the plastic fuel line connects to the injector rail.

You did not mention replacing the fuel filter. Is it new? A fuel pressure/volume test or a new fuel filter would be a reasonable place to start

You mentioned replacing the Air mass meter - were you talking about the temp sensor in the intake hose and/or the MAP sensor connected to the intake manifold?

 

Thanks for the reply. I replaced the temp sensor in the intake hose, directly after the airbox. I have not replaced the fuel filter yet, but I had read these large canister filters rarely clog, and this one looks newer. I think I do have a spare so maybe I'll try that next. I know my 940 has a connector for a pressure gauge underneath, however I don't remember seeing one on this car, I'll give that a shot.

Interestingly I just got back for a drive and it threw a CEL. Ran the codes at it was 1-2-3, faulty temp sensor signal. Seems odd as it's the first time this has popped up and car has no problems starting. I reset the code and will see if it reappears.

 

that sounds like fuel flow not pressure...

you can use a T adapter that you put between the fuel line and the input side of the fuel rail to measure fuel pressure, but that will just measure the pressure at idle with no load unless you can somehow rig it up so you can read it while driving...

another possible candidate would be the MAP (mainfold air pressure) sensor that Regina uses instead of hte MAF (Manifold Air Flow) meter that Bosch LH uses, , but I've never had a car with that so I don't know much about them.

 

Well decided I'd change fuel filter before measuring pressure. Of course I busted the rusty feed line from the tank to the filter, go figure. Line from my parts 940 is different so will have to wait to continue troubleshooting until I order or fabricate some kind of replacement.

 

the other potential cause of fuel starvation is the fuel pump, which on a regina system is inside the gas tank, attached to the fuel level sending unit.

 

Finally had time to work on the car and it's now running like a top . However, I never really found out exactly what the problem was because I more-or-less took a replace all approach. I had previously swapped the cluster out of my parts 940 in so I had a working speedo, so I figured i'd swap the sending unit/fuel pump as well so the fuel gauge worked, and replaced the sock filter on the pump while it was out. Repaired the broken gas line with a 5/16th nylon patch and replaced the canister fuel filter. So apparently it was fuel related, just no sure what part. If I had to put $$$ on it, I'd say fuel pump was on it's last legs and struggling to keep up.