1990 B234F - a few questions

[3wagons]

I picked up a semi running B234 740 earlier this week. It was parked when it started running rough. I have checked the timing belt and it is correct, not jumped or anything. It fires up and runs rough almost like a bad MAF. Also wont idle without giving it gas. I haven't had time to dig into it yet and see find the issue yet due to work.

My first question is what parts interchange injection wise from a B230? I believe I have read that the MAF is the same. Are the temp sensor, fuel pressure regulator etc all the same as the 8 valve? Same distributor as a 8 valve motor?

Also, key on, the HP fuel pump primes for close to 20 seconds. I have not verified in tank pump operation yet or fuel pressure. I have owned several 7/9 series cars and never have had one prime this long. Is this normal for the B234? Also, if you cut the key back off while its priming the pump continues running for a few seconds, usually around 20 seconds total.

What should the fuel pressure be?

Thanks

 

[oldschoolvolvo]

A B234 runs on LH2.4, so the sensor components are the same as the B230 engines running LH2.4. The fuel/ignition computers are unique to the B234 tho.
Fuel pressure is 3 bar.

 

[ZVOLV]

Oil leaks into the spark plug wells.

 

[ZVOLV]

The cap is the same, the dist base is not. FPR is interchangeable. MAF is the same.

 

[3wagons]

A B234 runs on LH2.4, so the sensor components are the same as the B230 engines running LH2.4. The fuel/ignition computers are unique to the B234 tho.
Fuel pressure is 3 bar.

The cap is the same, the dist base is not. FPR is interchangeable. MAF is the same.

Thanks! I should have plenty of spares around then.

Oil leaks into the spark plug wells.

Judging by all the oil around the valve cover, solid chance this is going on. Would this cause misfires?

 

[tbrcktch]

Thanks! I should have plenty of spares around then.


Judging by all the oil around the valve cover, solid chance this is going on. Would this cause misfires?

Not uncommon leak for 16 valve, it can (a lot of oil / loose plugs/ damaged plug wires), but doesn't necessarily mean it'll misfire if it's got some oil in the well. Good luck!

 

[3wagons]

2 inches of oil in 1 and 2, almost an inch in 3. At least 4 was clean. New plugs, wires, and cam cover seal should be here tomorrow hopefully.

May not be the whole issue, but it's a good start.

Also, fuel pressure was 46 psi with key on. Maintains at least 20 psi after an hour. Fuel pump cut on with key on, and off with the key off. Still going to have to dig into that.

 

[hessam69]

Something is up with the fuel pump relay or ECU if it runs the pumps for that long

 

[3wagons]

Something is up with the fuel pump relay or ECU if it runs the pumps for that long

I've swapped relays. Going to dive deeper sometime this weekend. Curious to see if the ecu is keeping the relay latched or if its another issue.

 

[oldschoolvolvo]

Wow! That’s a lot of oil in the spark plug well.

 

[tbrcktch]

2 inches of oil in 1 and 2, almost an inch in 3. At least 4 was clean. New plugs, wires, and cam cover seal should be here tomorrow hopefully.

May not be the whole issue, but it's a good start.

Also, fuel pressure was 46 psi with key on. Maintains at least 20 psi after an hour. Fuel pump cut on with key on, and off with the key off. Still going to have to dig into that.
View attachment 22098

Odd place for additional oil dip sticks! On your fuel pressures: key on, pump on, 46 psi, / key off, pump off (after relay finishes its timer), 20 psi after an hour? Sounds like good system pressure, and good rest/residual pressure. ??

 

[3wagons]

Odd place for additional oil dip sticks! On your fuel pressures: key on, pump on, 46 psi, / key off, pump off (after relay finishes its timer), 20 psi after an hour? Sounds like good system pressure, and good rest/residual pressure. ??

Yes, but the pump is priming for 20 seconds or more instead of the normal couple seconds. Yesterday doing the fuel pressure test, it ran for probably a minute before I cut the key off. I'm going to dig deeper into it today or tomorrow.