Hi guys,
I'm a 240 guy that just broke out of the mold and bought my first 740. It's a 1991 and it has what I was told is the Rex Regina system. I've worked on hundreds of 240's with the Jetronics systems and I feel pretty confident about my abilities but this looks more like a GM type system.

I bought the car thinking it just had a bad AMM only to find it doesn't have one. The car would crank and idle really low and if you babied the throttle it would run pretty well but it still wasn't drivable. As it was running just off idle it smelled as if it was flooding and then it started to miss one cylinder at a time until it died. After it dies I couldn't get it to restart it would only hit every now and then as if it fouled the plugs. The previous owner said he had recently installed new plugs and wires which makes me think this is not the first time it's done this.

HOw does this system work? Is the sensor in the intake hose a IAT (idle air temperature) sensor? Will it cross with any american car? Does it have a MAP sensor? If it is flooding can I troubleshoot it similiar to the same condition on a Jetronic system. Will it run with the O2 sensor unplugged? Can I force it to run in an open loop with the sensors unplugged? I'm sorry for all the dumb questions but I really need to drive it home (about 10 miles).

It has a check engine light on. can the codes be checked like on a 2.4/3.1 system and are the codes the same?

Thanks so much for your help.

Tony T
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Tony Turner 89 Volvo 240DL 257K, 1980 Mercedes 240D 360K, 1982 Mercedes 300D Turbo Diesel 153K, 2 1992 Geo Metro Convertables (I'm not sure why??)

Good morning everyone,
Thanks to all of you for the replys. I called a friend (dhalljr from the 200 board) and we went to get the car yeaterday morning. Dhall has had a lot of experience with the 700 series cars so he was a huge help.

Once I got it straight in my mind that it was more like a GM system and after reading the FAQ I was a lot more confident.

The first problem we tackeled was to make sure it had enough gas in the tank to run. The gauge had the light on but it didn't show completely out of gas.

Next we were able to get the car to run (most likely it was out of gas) even though it didn't idle and it ran badly. Dhall said it seemed like it had a vacuum leak so the hunt was on. As I looked around the manifold and throttle body two of the elbows had HUGE holes in them (the biggest hole was in the line to the MAP sensor)and the line to the flame trap was cracked. We replaced the elbows and lines and it ran beautifully. I drove it home and it runs GREAT!!! My daughter is VERY happy with it and feeling less upset about her wreck that totaled her Mercedes 240D (her baby as she called it) earlier this week.

I have to say that this is the best riding and driving Volvo I've ever owned, and I've owned a bunch. I'll be fixing a lot of tiny little things but it's basically a daily drive as of right now.

Thanks again for all your help,
Tony T
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Tony Turner 89 Volvo 240DL 257K, 1980 Mercedes 240D 360K, 1982 Mercedes 300D Turbo Diesel 153K, 2 1992 Geo Metro Convertables (I'm not sure why??)

Once I got it straight in my mind that it was more like a GM system and after reading the FAQ I was a lot more confident.

Glad to hear you got it fixed, Tony. But Don't get too "fixed" on it as being more like a GM system (of which I know nothing). Except for the MAP, Air Temp, and O2 Sensors, it seems pretty much like the LH 2.4 to me.

I have the greenbook diagrams for the '93 940, which include the LH and EZK circuits for b230 F and FT. I compared the Regina and LH ECUs and all wire colors are the same, pin for pin, except a few that one system or the other doesn't use.

Regina uses 24 pins
LH uses 30 pins
21 pins are functionally common to both systems

Some controversy about Fuel Pressure Regulators -- different Part #s and Regina more pricey. But both systems have the same pressure specs (43.5 psi with vac hose off and plugged. About 9psi less at idle with vacuum.)

The titania O2 sensor is more expensive too, but it has some redeeming features, such as: quicker warm up, no need for reference air, and a couple more things that escape me now.

EDIT: As for that funky coil, I've heard of a failure or two, and that they cost a lot.

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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

Anecdotal evidence seems to say that the titania O2 sensors last a lot longer than the common zirconia ones. Maybe because they don't have to allow in outside air, moisture etc ?

Don't believe the fcpgroton site that lists the generic Walker sensor for the Regina cars. I love those guys in general, but I told them a couple of times that the Walker (zirconia) was wrong for Regina, but the site still lists them.
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Andy in St. Paul. '89 244 153K mi, '91 745 Regina 202K, '88 244 184K

Congratulations on your new ride.

It could certainly be a lot of things, but my experience, and from what I have read on the board, says there are very few problems with the engine sensors in these cars.

Do you have any oil leaks? The Distributor os at the very back of the engine block on these cars and oil can leak into the dist cap. This will cause you to run more and more poorly until it will finally make it quit starting. It's a little harder to pull than on the Bosch cars: just three bolts, but it's a little tight. You might want to pull it to check the condition of the cap and rotor besides checking for oil. If you do have significan oil in there, you may need seals, but you probably have a problem with the flame trap (PCV) system you should clear first.

I wouldn't think fuel pump first. I would expect that to be more of a problem when revved up if the pump were failing and I don't see how this would explain the cylindars dying one at a time.
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Andy in St. Paul. '89 244 153K mi, '91 745 Regina 202K, '88 244 184K

Hello Tony; You are correct in that it is very close to a GM injection system. It has a MAP/Baro sensor ( over on the drivers side strut brace, check the rubber connector elbow for cracks) that is a GM Delco part. It is also very close to the early 90's Toyota 5sfe 4cyl engine systems, one of the most reliable on the road. I personally feel that they are an easier system to work on, and would even say more reliable, no AMM to deal with. Even cheaper, the map/baro is about $40 if you cross reference it to the GM part, ie 1990 Chevy Celebrity w3.1 v6, same part. The intake sensor is a temp sensor, and it uses a Titania O2 sensor. They have a fuel pressure regulator, just like the LH, and it may be bad if it is getting too much fuel. The trouble codes for the Regina's ( different than LH) are in the FAQ. Never tried running with the sensor removed.
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Gary Gilliam Sumerduck VA, '94 940 na Regina 160k '86 240 190k

O.K.
I went and read the FAQ and it answered a lot of questions but I'd like to here what you guys with experience have to say.

Thanks a bunch for your help.

Tony T
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Tony Turner 89 Volvo 240DL 257K, 1980 Mercedes 240D 360K, 1982 Mercedes 300D Turbo Diesel 153K, 2 1992 Geo Metro Convertables (I'm not sure why??)

Hi Tonky-

I'm not much of mech, but I have done a lot of research on the Rex/Regina system here on the BB. I used to have all the good ones bookmarked but, sadly, once my problem was fixed, I deleted them in ritual of celebration. I will say this: Rather than go sensor by sensor, I would start at the fuel pump. I've gathered that the fuel pumps on these go bad earlier than the Bosch pumps.

I made the mistake of replacing the IAC, the FPR and even the knock sensor before looking at the fuel pump. If your 91 has over 150k, you might want to do the fuel pump just to be sure.

I'd make sure your fuel pump is good, then look at the FPR, then the IAC, after that, it could be an ECU issue. Sorry I can't be more specific. Good Luck!

My '93 940 is about 148K now. No problems in the 2 1/2 years I've had it, but I have also heard that the pump isn't as long-lived as the Bosch. So I'm thinking I need to be prepared.

Where did you source your replacement? Do you recall the brand and price?

How much hassle replacing it?

Can/did you swap over the fuel sender?

I've done 240 feed pumps, but haven't seen the 700/900 pump/sender area (yet).

I'm sure Tony will also be interested in your experience in this area.


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Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

I got the pump at FCP Groton. It looks like they have it for 105 bucks right now. I seem to remember the box being labled "San-Tech" which, probably, may not have been the best choice.

As for the hassle, I have to be honest: I got that access panel off, when I took one look at the fuel lines and wiring running to the pump mount, I realized I was out of my league. The next time I took the car in, I had the mechanic install the pump. I have a tendency to break things when I try to fix them and there didn't seem to be much margin for error in this stiuation.

I'm pretty sure he used the same sender. I think if you've done an in-tank pump on a 240, the 740 shouldn't be a problem.

Hope this helps!

MP