I got my 1990 volvo 744t (bosch lh 2.4) about three weeks ago. It ran fine up until a few days ago when it began sputtering quite often at lower speeds. It seems to me like it's starving for fuel, but this only occurs while city driving. When I'm traveling on the highway it doesn't occur, or if it does I don't notice it. I've jumped the fuel pump relay and can hear both pumps. I swapped a fuel pump relay in from a 240 parts car I have. Does anyone know what this sounds like? I'll admit that I ran the car pretty low on gas and that's when I noticed it. From what I've read I think it sounds like an in-tank pump issue. Does this sound right or should I look in another direction? Coil, distributer, plugs, wires were all done in january (po kept receipts). Any ideas?
Thanks in advance

 

I dunno, but fuel pressure or volume problems usually happen at high speed high throttle full load kind of driving.

low speed problems could be a air or vacuum leak in the various hoses, could be a problem with the idle regulator thing if it only happens when you're stopped and idling.

lots of troubleshooting tips here
Volvo Maintenance Hints for 7xx/9xx

 

My 740 main fuel pump is pretty noisy. Whines loudly even though it's new. My dad tells me that both of his volvo's (940 sedan and 740 wagon) both had noisy fuel pumps so I'm guessing it's normal.

First thing to figure out is whether it's a fuel issue, mechanical issue, or ignition system issue. Problems in any of those areas can cause your car to run lousy. I like to put gauges and and a multimeter on stuff and test it. Just make a list of all of the big things in each of those categories and start testing. An easy way to check the in tank pump is to pull the fuel line in between the two pumps. Have a lovely assistant turn the ignition and you watch for gas to squirt out of the hose. If you want to go into the tank and really check it out, replace the filter on the in-tank pump. I promise you it's filthy.

 

my 740's main pump was noisy when the tank pump was broken. fixed the tank pump and the main pump became almost silent.

getting the tank pump+filter+fuel level sensor assembly out of a 740/940 tank is a pain in the butt. getting it back in correctly is even harder.

 

Installation is reverse of removal though right!?

 

the hard part is, the black clamping ring often warps after its removed and won't go back on the threads on the tank. also getting it in and out requires a fair amount of contortion as the baffles inside the tank make it so you can't just insert it sideways then rotate it 90 degrees.

 

Fuel starvation isn't fuel pump at low speeds, keep looking.

 

Ok, I checked for vacuum leaks and everything appeared to be alright. I cleaned the tb/replaced gasket, replaced the pcv, cleaned the iac valve, and had the fuel injectors cleaned/replaced o-rings, caps, and baskets. Car seems to run worse now. At idle in neutral it's fine, when I first drive it seems to misfire, then when I stop it stalls and keeps stalling when put into drive unless I give it gas. I'm getting code 2-3-2 with the pin in position 2.

Possibly the FPR? I feel like I'm overlooking something basic here.

 

code 2-3-2 means its running too rich or too lean. could be lots of reasons for that. pull a spark plug, is it white, grey, or black? thats lean, normal, rich.

pull the vacuum hose off the front of the fuel pressure regulator, if any gas spurt out, its shot, you need a new FPR. if its dry, put it back on, start the car, and pull it for a second while its idling, and it should run too rich, which depending on whats wrong might make it stall immediately or actually idle better.

testing fuel pressure requires a fuel pressure gauge with volvo specific attachments, this is something you let a volvo mechanic do for you, its a 5 minute test. you should read about 42-44 PSI above the manifold pressure... manifold pressure is typically -7 or -9 PSI at idle with the throttle closed, in a normally aspirated car its 0psi wide open, but with a turbo its +9 PSI or so wide open.

 

I finally broke down and took it to my local volvo shop. Turns out the cam timing was off by two teeth and the p.o. installed the aff backwards. Car runs like a dream now.

Big thanks to all who offered suggestions. This is one of the most friendly/helpful forums I've come across.