1989 740 ECU got wet

Buckeye740 · Post by **Buckeye740** » 22 Jul 2015, 20:26

Need some advice about what happens when your ECU gets wet. I ran into high water during a storm and I have a hole in the passenger floorboard. The Bosch 951 ECU got wet on the bottom. I got about a mile down the road before it quit. Crank, no start, flooded. Since then, my electronic repairman cousin has taken a look at it and found a shorted transistor at the bottom which he replaced with an equivalent. But, I'm still having problems. When cranked, the car floods instantly. I have spark, I have fuel, probably too much fuel, but no go. Cousin thinks I got a power surge when the transistor went out and fried an IC. Plugs are wet with fuel. Also, when I tried to check for codes on the OBD #2 socket, the light comes on when the key is moved to position 2 and stays on. The ignition side of the OBD works fine and flashes 1-1-1. Anybody have any experience with a wet ECU? We tried simply drying it, and also the aforementioned transistor replacement. Cousin also feels the injectors aren't pulsing, but pumping constantly. If you take a plug out and crank it just a little it'll quickly wet your arm that's clear out by the fender!

lummert · Post by **lummert** » 22 Jul 2015, 21:12

Find a good used ECU.

93Regina · Post by **93Regina** » 22 Jul 2015, 21:26

lummert wrote:Find a good used ECU.

Crush It

Buckeye740 · Post by **Buckeye740** » 22 Jul 2015, 22:22

Got a replacement on the way. I would crush it, but it only has 250,000 on it, and I'm just too poor to buy another vehicle right now. Thanks for the replies, but I was hoping someone with some experience might point me to what circuit within the ECU has gone bad, for future reference. Also, I'm not hearing the little whirr from the fuel pump that I usually do when the key is first turned on, like the fuel system is staying pressurized. Right now, the Volvo you pictured 93Regina would do good in front of my house and several miles in either direction as they are repaving.

mika · Post by **mika** » 23 Jul 2015, 11:57

one thing at a time. If you car was working fine and then wasent, don't be worried about fuel pumps or other stuff. Drop a new ECU in and see where you are then. I understand how an issue can turn into a nightmare temporarily, but don't loose sleep over it until you get the new ECU in. keep us posted

Buckeye740 · Post by **Buckeye740** » 23 Jul 2015, 13:10

You have that right mika, head is so full of possible things that could have gone bad downstream of the ECU, and it's compounded by the fact that one way or the other, the car must be moved. The garage lot that I pushed it into is very busy and they've been very understanding, but... Note, I got it to a garage, but don't have the money to pay them to work on it. If I found someone to pull it, that would be compounded by music festival traffic on the route, etc. Thanks, reading "one thing at a time" does wonders.

93Regina · Post by **93Regina** » 23 Jul 2015, 23:36

Buckeye740 wrote:If you take a plug out and crank it just a little it'll quickly wet your arm that's clear out by the fender!

LH 2.4 uses a ground to energize all injectors at the same time...pull all injectors out, and test.

93Regina · Post by **93Regina** » 23 Jul 2015, 23:40

Buckeye740 wrote: Also, I'm not hearing the little whirr from the fuel pump that I usually do when the key is first turned on,

ECU Fuel Pump Control Circuit Repair.

Buckeye740 · Post by **Buckeye740** » 24 Jul 2015, 00:37

Thanks for the info Regina93. I've dug around enough to find the Bosch driver ICs are available and inexpensive, so I might just get the old one fixed, without paying someone $375 to do it. Cousin will understand the page you linked to better than I do, but I get the main drift. I'll print it out for him.

Buckeye740 · Post by **Buckeye740** » 27 Jul 2015, 16:32

I got the used ECU installed. Some things got better, but it still won't start though it has both spark and fuel. Now there isn't too much fuel, and the light that was stuck on the OBD#2 has gone out. Checked for codes after a bit of cranking, both sockets 1-1-1. I thought it was going to take off when I first cranked it, fired a few times, but no go after that. At least I got it moved to where it won't be towed away. Found a cousin a couple miles away that has a big lot. I also installed a new Ignition Control Module. I've got some time to ponder any advice received, won't be able to get back to it for at least a week.