Need some advice, 88' E34 525i.

[E34_525i 0]

I'm usinf my mates account to post this, as I tried for ages to create my own account, but the website kept saying I got the code wrong/asking me questions I had to google the answer to. (I'm not a beemer guy)

Anyway,

I've been helping my mate try and fix his 1988 NZ new factory manual E34 525i.

It has the single ohc M20B25 engine.

About 18 months ago, it dropped a cylinder. He tried swapping out the injector, and the spark plug and lead. Turned out it had two broken rocker arms/cam follwers. even swapping those didn't bring it onto all 6.

So Rather than trying to fix it, he started swapping in another engine from a donor car he bought. The previous owner of that car suposedly had $3k in recipts for having the motor overhauled. (My mate didn't get the recipts, so like "it's got a fresh engine bro" on trademe, we have to take that with a grain of salt) That said, it was VERY clean under the cam cover. The cam was in very good condition. (unlike the old motor, where the cam was f-d)

He got the replacement longblock bolted in. Then life dished up one of those curveballs, (sh*t happenes) and the car was parked up untill now.

Her indoors has decree'd that he has too many cars. (He does too) and after he bought another one recently, the beemer has to gtfo.

So we've started trying to get the bastard running.

Which brings us up to where we're at now.

We refitted the injection manifold, and reconncted all the plugs etc. Hooked the fuel and return lines up the fuel rail.

After much time was spent doing battle with it, the damn thing refused to fire.

I pulled the line off the rail, and no gas comes out when the the key is turned/when cranking. I don't know bout bmw's, but nissans prime the pump for a few seconds when the ignition is switched on. We aren't seeing jack sh*t. (it aint never gonna go till we do)

The annoying thing is that apart from the motor running on 6, it still ran prior to being torn down.

Before I resorted to asking here, I did some googling. I read somewhere that some BMW's rely on there being spark before the fuel pump will pump? (Which sounds crazy if you ask me) Now I don't know if that's the case with this car, but there is some kind of pulse sensor(?) on number six spark plug lead. We found a plug on the loom which seemed to fit the plug on the other end of this "sensor". Also, given that car makers love to change things with no good reason, we reused the manifold, tps, afm etc etc off the OG motor from this car.

The workshop manual we have ins't very good.

Any idea where I can find the fuel pump relay?

Also, the oil level sender fault is coming up. (I didn't see this, but my mate said it said this) He thought maybe that's why it wouldn't go? (I doubt this)

Where is the oil pressure switch on one of these? The one in the bottom of the sump looks more to me like an oil level switch. (And old 13B I had once had one of those) My mate is going to swap the og one back onto the new engine.

Sorry about the essay. Also sorry if I should have searched for the answers.

Any advice would be appreciated.

[_ethrty-Andy_ 2132]

what year and model is the donor car? E34 or E30 or E28 etc?

the fuel pump normally does prime for a few seconds when you first turn on the ignition from memory

but it does check for spark on cylinder 6 as it is cranking, and yes using the cable you have identified

also check that the crank position sensor is at 540ohms +/-5% with a multimeter, to check this you can either unplug the DME/ECU and check between pins 47 and 48, or unplug the connector under the intake manifold and check the two pins there.

the fuel pump relay will be just in front of the shock tower in a little box along with two other relays, usually this relay is blue and in the middle of the three relays, and will have 4 pins

the white one in that box is the main relay which will have 5 pins

take off the fuel feed line and turn the engine over for a few seconds (good idea to put the hose into a 1L milk bottle or a jam jar etc) and see if fuel comes out. if no, check the one you believe to be the return.

an M20 engine will run without oil, (though not for long, and don't ask how i know...) thats one of the only basic self checks the engine doesn't really do

post back after you had a look at these things

Edited December 29, 2013 by _Ethrty-Andy_

[E34_525i 0]

Thanks mate!
That's the kinda advice I was looking for.

Where is the ecu located? And are the pins numbered, or do you have a pinout?

The manual my mate downloaded is better than nothing, but the wiring diagrams are pathetic.

I did still the hoses into a receptical prior to key turning.

[_ethrty-Andy_ 2132]

DME/ECU you should have already found, if not have you even plugged it in the motor swap???????

It is in the Black square box against the firewall on the right hand side of the car (in front of the driver in our case). There are three rows of pins and the ones on each end (so 6 of the pins) are numbered, from there you need to count backwards/forward to find the right ones.

Would be a good idea to find an ETM (electronic troubleshooting manual) for your specific car if you continue to have problems, but in the mean time anyways, below is a link for an E30 325i facelift one which is the same engine as you are using, jump to page 1360-2 and you will see the crank position sensor connecting to pins 47 and 48

everything to do with the engine on the E30 325i facelift will be the same as your M20 E34, what this link won't be accurate on is component locations in some cases, thats why you can find one in your own time if you do continue to have issues.

http://www.armchair.mb.ca/~dave/BMW/e30/e30_89.pdf

let me know either way if you have any more questions for tonight, i am about to jump off here and go to bed but id rather not leave you hanging if you want to get stuck in in the morning

[E34_525i 0]

Thanks Andy!

We didn't remove the ecu, as the loom was never removed from the car.

My mate only has the stats off. but I'll txt him to print off that stuff while he's at work today.

I don't think we changed the CAS, so that could be faulty. We still have the complete parts car. So swapping any bits or bobs is no problem.

As always, it's just process of elimination. But you need to know what you're looking at, to reach the finish.

Thanks for the helps guys.

Great forum!

[_ethrty-Andy_ 2132]

i have a complete (in terms of it starts and runs) M20 E34 here so if you want to cross check anything with another working car the same let me know