I'm so sorry for posting this again but I think it was lost in the shuffle yesterday morning. Let me add to it that the problem has not cleared up, it only does it after I've driven a hundred miles or more and Sunday was not the first time it has done it. I have replaced the Idle Air Motor just because I had one but there was nothing wrong with the one I took off (it didn't even need cleaning).

So here we go again ***********

I took my 89 244 on a nice long trip over the weekend and it ran well execpt for one little problem. After I had driven 125 miles on Interstate and then exited to a stop at the bottom of the ramp, she didn't want to go. As I accelerated from the stop light she started to surge REALLY bad. The car had ran perfectly on the Interstate and idled perfectly at the stop light. The light turned green, I started to accelerate. Just as I came off idle I hit a HUGE "flat spot" and the enginne almost died. I backed off the throttle and she caught up but the engine lurched into a series of surges as if it was running out of fuel. Next stop light it did the same thing but after it gets past the initial bucking and snorting she levels out and runs fine. I pulled back out onto the Interstate, she came up to speed just fine and I cruised along at 75 mph for another 100 miles with no problems at all until I exited again. We drove about 450 miles total and it only acted up for the first few stops after we had driven for a long while.

I drive this car everyday and it has never done anything like that. As a matter of fact, I drove it to work this morning (24 miles) and it acted normally. My first thought is fuel system. I'm leaning toward the Fuel Pressure Regulator because it does it after it has idled for a little bit (at high vacuum and then the vacuum drops rapidly as you accelerate) and then levels out as the engine comes up to speed and the vacuum starts to climb. Of course I could be wrong.

About 4 months ago I replaced the pre-pump and strainer, the fuel pump and filter, the AMM, the throttle switch and the ECU. All of those parts were required to get it to run after I bought it. I didn't use a Volvo main pump. I bought a Bosch "Universal" replacement pump (a fraction of the price or the Volvo pump). The Bosch looks just like the Volvo pump execpt the mounting is a little different, it had the check valve and everything. The pump sounds normal even when it is acting up.

Am I on the right track or chasing rabbits in the wrong direction??

I value your opinion ---- thank you.

Tony
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Tony Turner 89 Volvo 240DL 257K, 92 Jeep Cherokee 250K, 93 Jeep Grand Cherokee 215K, 1980 Mercedes 240D 360K

Long shot:
Check the condition of the bellows hose between air filter box and throttle body. Mine used to collapse under the increased air flow sucking through the filter when I stepped on the gas. It can get softer and more pliable when heated up. It collapsed and choked air flow when stepping on gas, release peddle and or rpm's go down and it pops out again. Then it will repeat the cycle again.

The Volvo pump is quite possibly made by Bosch, I don't think Volvo really make pumps. The pressure is controlled by the fuel pressure regulator not the pump. Pump is likely not the problem. Fuel pump relay is more likely, they can do funny intermittent things.
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David Hunter

Long shot:
Check the condition of the bellows hose between air filter box and throttle body. Mine used to collapse under the increased air flow sucking through the filter when I stepped on the gas. It can get softer and more pliable when heated up. It collapsed and choked air flow when stepping on gas, release peddle and or rpm's go down and it pops out again. Then it will repeat the cycle again.

The Volvo pump is quite possibly made by Bosch, I don't think Volvo really make pumps. The pressure is controlled by the fuel pressure regulator not the pump. Likely not the problem. Fuel pump relay is more likely, they can do funny intermittent things.
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David Hunter

I'm not discounting the relay idea because they are easy to repalce and cheap but I'm not sure if that could be the problem. Let me explain my logic and as usual I could be wrong.

I've had fuel pump relays go bad before and they did make my car surge and then quit. The surging, once it started, would not go away until the car either quit and then you let the relay cool off or I thumped the relay really hard. I resoldered the relay and it worked fine until I sold the car.

My thought on the relay is that once it got hot it would act up whether or not I was driving 75 down the highway or sitting at a stop light. The symptom I have only does it when you start off from idle after driving at Interstate speeds for more than an hour. The car never acts up while I'm still out on the Interstate and it only acts up for the first few stop lights and then it clears up. If I pull off the Interstate and then pull right back on the car will surge while I accelerate but once I level my speed off it runs great.

I'm going to go ahead and replace the relay and throw the one that is on it now in my spare parts box in the trunk. If that fixes the car I'll open up the old one and try to fix it. If it does no good at all I'll have the satisfaction of knowing I have a good relay on the car and a good spare.

Thanks for your help,
Tony
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Tony Turner 89 Volvo 240DL 257K, 92 Jeep Cherokee 250K, 93 Jeep Grand Cherokee 215K, 1980 Mercedes 240D 360K

YOU MIGHT WANT TO GET A NEW FUEL PUMP RELAY. I KEEP A COUPLE HANDY FOR WHEN THE ONE IM USING OVERHEATS AND CAUSES THE CAR TO SURGE, BUT ONLY AFTER A LONG TRIP.

Thank you so much for you execellent suggestion. They're cheap and easy to change on the fly --- very easy to test on a long trip.

Thanks,
Tony
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Tony Turner 89 Volvo 240DL 200K, 92 Jeep Cherokee 250K, 93 Jeep Grand Cherokee 213K, 89 Volvo 240Wagon 303K

Myfirst thought as I was reading your post was the TPS, but you mention it was replaced. Are you sure you adjusted it correctly? Do you have a Bentley manual? It doesn't sound like a FPR problem, but that's easy enough to check.

Yes I do have a Bentely manual. I adjusted the TPS to where I could hear it click just as the throttle opens.

I guess I ruled the TPS out because the car runs fine every day, I only seem to have problems after I have driven a long time at Interstate speeds. The other crazy thing is it only acts up after the first few stops after a long run. If I stop to get something to eat or gas and then start back up again it runs fine, until I drive a long way again.

It really does feel like a fuel issue. I even thought that it may be a fuel cap. If for some reason the little vent hole on the cap was not letting in enough air I guess it could make it harder for the pump to pull/push gas from the tank. When I worked for Dodge may years ago I worked on a D50 pickup that did kinda the same thing. On the D50 it had collapsed the fuel tank from not pulling enough air into the tank. I found the problem because the owner said he couldn't put as much fuel in as he once could. New tank, new gas cap and he was on his way.

The fuel pumps never change sound as if they are working any harder or sucking air. I guess it could even be an in-tank strainer stopping up and the crud falling off after I turn the enging off. It may even be a filter doing the same thing. I'm really a bit confused and I don't want to start replacing "expensive" parts just yet. I had hoped someone would say "hey! I had the same problem and it was XXXXX". Problems like this drive me crazy because I don't have money to just throw at parts to check it. I really wish I'd bought a Volvo main pump instead of the "Universal" pump that I used. It just puts that little doubt in the back of my mind. I keep telling myself that its still a Bosch pump and the only thing different is the way it mounts but I can't help but wonder.

Tony
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Tony Turner 89 Volvo 240DL 257K, 92 Jeep Cherokee 250K, 93 Jeep Grand Cherokee 215K, 1980 Mercedes 240D 360K

I think you're on the right track suspecting the fuel pressure regulator. Check it according to the FAQs on this site. See if you can find a cheap one at a junkyard to swap out.

I'd also suspect the gas cap. If it's not venting properly, it would create a fuel starvation problem after a long drive. Get a new one, since they're inexpensive.

Best regards,

Tony
'88 244 GL

How long has it been since the throttle body was removed and given a good cleaning, along with the vacuum lines on the part?
Poolman

I haven't done that since I've owned this car. It looks good but that may just be a good project for this weekend --- it couldn't hurt.

Thanks A bunch,
Tony
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Tony Turner 89 Volvo 240DL 200K, 92 Jeep Cherokee 250K, 93 Jeep Grand Cherokee 213K, 89 Volvo 240Wagon 303K