I am about to buy some parts to finally getting my 94 940 non-turbo running. It is having trouble when the engine is below 1500 rpm and wants to cut out. Above 1500 it runs like it should. If I turn the air on the car wants to run rough and tries to drop rpm's. It really seems like the car is not getting gas at low rpm's.

I saw @jagtoes post earlier about troubleshooting. He said:

1. Do you have spark
2. Do you have fuel pressure
3. Did you check fuel pump relay/relays
4. When did you last change fuel filter
5. Are your fuel pump/pumps running

It does seem to have spark, but how do I check fuel pressure? I have tried jumping the pumps but I didn't see a difference. Maybe I didn't do it right. I am about to change the fuel filter. I was thinking I would also change the in-tank pump. I was told by the previous owner he had changed out the Regina pump but not the in-tank. On a 940 how can I verify that it is the back pump? How hard is it to change it out?

I don't have a lot of money and I don't want to waste what I have buying a bunch of parts I don't need. Any help would be appreciated.

 

Stop. Let's think this through. Bad fuel flow is exacerbated with greater engine demand, ok? The faster the engine runs, the more fuel it needs. The least demand is at idle. Your car runs fine at higher RPM's and idles like crap. Pretty safe to say it is not a fuel issue. Most common is one or more vacuum leaks. The simplest way to check for leaks is with propane. If you have a torch, remove the flame head and lide a 2-3 foot piece of hose over the end. Propane will make the idle go up significantly when held close to a leak. You do not light the propane, ok? You merely crack the valve a bit and hold the tip near all possible areas where there could be a vac leak. That includes all the vac lines, all around the base of the intake manifold, the brake booster and, in your case, the idle air control valve.
First, let's explain the difference between Regina systems and Bosch systems. Without going into details, the Bosch cars have 2 fuel pumps while the Regina cars only have an intank pump. The simplest way to quickly determine which system you have is to pop the hood and look for the ignition coil.
If it looks like a traditional coil...

you have a Bosch system. If it looks squarish, like this...

then you have a Regina car.
Your Idle Air Control valve (IAC) looks like this on a Bosch car...

If you have a Regina, the IAC will look like this...


In either case, there will be 2 large hoses connected...make sure they do not leak. Also, there is an electrical connector...check to make certain it is well connected.
Check in with us when you're done.

 

Thanks for the great detailed post! I hooked up my propane tank from the grill to be sure I had a good source. The good news is that I lived, the bad news is that I didn't find a leak. While I was testing it I could hear a noise coming from the engine when I revved it up.

I have some videos of the car running. Maybe that will help. Sorry for the choppy video!

Video1: 1994 Volvo Running 2 - YouTube
Video2: 1994 Volvo Running 1 - YouTube

And BTW, it is a regina car.

Any suggestions on what I should look for next?

 

Any ideas what else I can look for? I really need to get this car running soon.

 

Just now viewed the vids. Sounds bad...but videos always do on the internet. Definitely hear a miss...bad plug, wire, bad dizzy cap/rotor kind of thing perhaps. I'd definitely pull the plugs and examine them. If not sure, feel free to take pics and post them here...makes things easier.

 

Would that cause the car to act like it can't get gas at low rpm's? I did replace the spark plugs but not the wires or distributor cap. I just got back in town but I will try and get new wires. The previous owner had put in some kind of spark plug adapters (quick hits?) and I am concerned that the wires don't fit as snug as they should on regular spark plugs.

 

It sounds as when you give it more gas that there is a miss in there somewhere like it's not quite hitting on one cylinder.

It also looks like it was stumbling on idle just a bit and under load got worse. I'd go with Swift on this one and say cap, rotor, plug and eliminate those. Pull the cap and rotor and see what the terminal ends look like, then go from there. I've had cases where one bad plug wire would result in the same symptoms.

 

Hmmm...I've not heard of spark plug adapters for red blocks...that sounds intriguing. I'm thinking this will be a simple fix. By the way, what brand of plugs did you buy?

 

I am putting parts together to buy now. I looked at the distributor cap I have and it looks like this one:
Volvo 940 8 Valve Distributor Cap 1993-1995 | 940 8 Valve Parts

But I don't know what rotor to get. I think it might be this one:
Volvo 940 8 Valve Distributor Rotor 1993-1995 | 940 8 Valve Parts

Spark plug wires:
1994-1995 Volvo 940 8-Valve Spark Plug Wire Set-Bosch

Anything else? I will double check the spark plugs I bought. I know the wires from the Direct Hits adapters don't fit good. I sure hope this gets my 940 running! Thanks for all of the help.

 

The D cap and the rotor are correct. There really isn't much option on 'em ...from 86 or so on, there's only one d cap and rotor on all the B230's. Plug wires are a bit different for Regina cars...the ones you chose are for Bosch ignition...I saw these are for Regina 1993-1995 Volvo 940 8-Valve Bougicord Ignition Wire Set

Also, a bit of opinion on spark plugs. There are certain brands of plugs redblock motors do not like...Champion is a no-no. So are Autolite, imo. NGK and Bosch have always been good choices along with Nippondenso. The standard copper plugs seem to work better than the new high dollar platinum ones.

 

The parts are ordered! Thanks for all of your help with this. I should have the stuff later this week. I will let you know how it goes. I can't wait to get this car going as my daily driver.

 

Put the parts in and the car ran great. I drove it around for a few miles and came home and turned it off. A few minutes later I came out and it is running bad again. I noticed that the fan never runs. It is not running hot but it doesn't ever have the radiator fan kick on. I disconnected the battery and pulled the fan. It spins freely. What else should I look for? I let it cool down and tried again and it idled ok but still didn't run right.

 

Are you referring to the auxiliary fan in front of the a/c condenser? From the factory, it only comes on under sever overheating conditions. It doesn't run w/ the a/c at all, not during normal driving. The simplest test is, with key on engine off, jumper the two wires at the back passenger corner of the radiator where the overheat sender is. Jumper them and the fan will most likely come on. Generally, the fan comes on too late to be of use. That you did not see it running is not cause for alarm.

 

I am talking about the fan that is mounted between the radiator and the serpentine belt. I am just trying to figure out why it still runs bad.

 

Ok. It has a dual relay setup. Those can occasionally go bad. It's a 2 speed fan...as I recall the low speed on it cycles w/ engine temp as determined by the ecu and high speed is determined by the a/c. So...if it's not coming on ever, I'd look first at the relays.

 

Where are the relays, or what do they look like/located?

 

It's a duplex unit and is clipped to the fan shroud...looks like this

 

Here is the car before and after putting it in gear.
Before: Before putting in gear - YouTube
After: After putting in gear - YouTube

You can hear that it is still running rough. I found that relay but I don't know how to test it. I guess I will need to pick one up. I don't know what else to try to get it running consistently. It is getting frustrating! I was so excited for a few minutes when it first ran.