NEED help diagnosing fuel/ignition problem.

[kidinthehall]

I'll try and condense this as best I can, so bear with me....

My 92 525i Touring recently died on me while at the gas station. It ran fine up to that point, but when I attempted to start it and leave after filling up....no start. The car would turn over fine, but wouldnt start. Figuring the fuel pump could have finally died (car has 300k miles) I walked over to a parts store and bought some starting fluid. After spraying a little in the throttle body and reconnecting the intake....the car fired right up and ran until it burned off the starting fluid. To make sure it wasn't a fluke, i tried it again and got the same result. So I tow the car home, and order a new fuel pump. After removing the old pump, and seeing that the pre-filter attached to the pump was pretty torn up, I put 12V to the pump and confirmed it was dead.

So, in with the new pump. Pretty straight forward, no problems. The only thing that seemed odd was that the replacement pump has a diaphragm of sorts attached to the outlet that the OEM pump didn't. (looks like a fuel pressure regulator with no vacuum reference basically). Now the fun part...... The car will not start. The new pump is working, the feed and return lines weren't mixed up, the main relay and fuel pump relay can be felt engaging when the key is turned.....but the car will not fire up, even after spraying a small amount of starting fluid in the intake. I also pulled one of the coil packs and spark plug and confirmed that it is getting spark (although the spark did look a little weak to me). So, I'm confused at this point as to how i apparently have fuel and spark....but no running car. I'm open to suggestions and certainly curious to hear what I may be overlooking.

Thanks
Chris

[whiskychaser]

Assuming your new pump is the correct one, check the fuel pressure test at the rail?
Your battery may have taken a bit of a hammering with all the attempts to start and that may be causing the weak spark. Maybe check / charge it?

There is an excellent 'thread to end all threads' about no start problems. Sadly, I cant find it. Hopefully someone else will be able to point you in the right direction

[roadsterred]

I agree with whiskychaser in doing a fuel pressure test first to eliminate the fuel pump as the cause of the no start problem. Unless the fuel pressure is up to specification, the fuel injection system will not work. Once you have confirmed that the fuel pressure is OK, you can then proceed to the ignition if the engine still does not start.

[SpiritofBavaria]

You might have purchased the wrong pump. The oem pump has no additional regulator at the top. The OEM Bosch pump for the E34 costs $110 shipped. Even if this one would work, you reconnected the fuel hoses or powering wires in the wrong direction i.e. its an installation problem.

There is no need to check for rail pressure. Your original test with the starter fluid was a positive, proving that you were not getting fuel at the rail. I'm sure you checked that your fp fuse is ok (check that now in any case). You suspected the pump, took it out, tested it and did not get continuity. Your problem here is the fuel pump, period.

A new pump will solve the problem. Something went wrong with the installation. Or perhaps the fuse suddenly went and merely needs to be replaced. Please recheck all of that.

If you wish to check rail pressure but do not have the gauges, very simple. Pull out the fuel hose at the rail at the front of the engine. Key2 the ignition. A little fuel should come out then it should stop. Then, jump the fuel pump relay (put the key to zero first, do not just this relay live). Fuel should spurt out continuously. Shut it down after 1 second, reconnect the hose, and hose off the fuel around the engine with 2 quarts of water.

These two tests must be done together, and if positive, show that the pump is working correctly 99% of the time. If that happens, then it is possible that you have a new problem. It would most likely be the fuel pressure relay. With the hose connected, jump the relay, then start the engine. If that works, then your relay is the problem. Get a new one, and drive with the jumped relay meanwhile. I've done this before for 2 days and it is secure if you use thick wires that are held fast in the relay sockets when inserted. Remove the jump whenever you shut down the car, if not it will drain the battery.


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Common E34 no-start problems (crank but no start)
[Check Fuel Pump's fuse and error codes first]

1. Fuel pump. (Do not mix up the in/out lines and + - pump wires during installation.)
2. Fuel pump relay/ poor fuel pump relay socket's contacts.
3. Crankshaft position sensor. (Do not misconnect with the wrong connector during installation.)

All these things must be changed when you first buy the car ([EDIT] : especially if your E34 is your daily, and/or you don't have reliable proof that they were done in the past 3 years). Don't wait till you get stuck somewhere. Towing and emergency repair charges are not worth it for such known issues. Oem parts for these three are under $250 shipped, so its cheap.

If you've done all of these and you still have a no start issue, don't feel stupid. You would've been whacked by the three stooges in due course.


Uncommon E34 no-start problems ( no-crank situations)
[Check Fuel Pump's fuse and error codes first].

1. Bad battery / alternator.
2. Bad fusible link.
3. Clogged fuel filter. (crank but no start)
4. Clogged air filter/debris in the air box. (crank but no start)
5. Busted EWS2 system ( key or immobiliser unit, and on 95 cars and later only).
6. Busted starter. Tends to be on high mileage cars only.

All these things must be checked when you first buy the car. Some cars have fuel filters that are more than 10 years old, so it should be swopped out new unless you have reliable records that it was done recently.

The EWS2 can't be checked, only prepared for. Purchase a used non-ews dme for around $50-$70 shipped off ebay and keep it with you to install should something unexpectedly happen. It can be sold off for the same price later if you sell off the car. Also, be familiar with the EWS bypass procedure.....have a printout somewhere in the car should you need to do this suddenly.

And if you ever remove the intake manifold to do anything, have the starter replaced or rebuilt. A new OEM starter costs around $150, and installation is very DIY. Especially if you have a high mileage vehicle, have a new starter on hand. Consider it cheap insurance, even if you have to take a $50 loss and sell it off someday.


Rare E34 no-start problems (crank but no start)
[Check Fuel Pump's fuse and error codes first].

1. Damaged DME. Crank but no start.
2. Busted fuses for the central locking system (?) under the back seat. See :

http://forums.bimmerforums.com/forum...3#post26038033

3. Busted engine coolant temperature sensor (blue tipped). When bad, you usually get poor economy, or hard starting either when hot or cold, but can sometimes turn into a no-start affair (lower compression M20 engines are probably more prone to this)
4. Busted vibration damper. Throws timing off. Caused by belts tensioned too hard by bad tensioners. Usually, there will be a fairly long period of deteriorating drivability before it the engine fails to start entirely.

5. Damaged/shorted wiring between the DME and the injectors or coils. No start, hard start, or start with a quick death and rough idle.


Check the fuses, have spares handy, and have a spare non-ews dme ready (if your car has an EWS2 system). As to the ects, its too important a sensor for precise engine running, your old sensor is nearly 20 years old, new oem one is too cheap (Bosch costs under $30 shipped), and its a less than 10 minute job for a mechanic to socket out from your current engine, for you not to change it out.

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[ross1]

Does it run with the starting fluid? It would be an odd coincidence but there could be other faults. Ign.?
How did you test the pump? Because the relay is clicking doesn't mean it's making good contact, a failing pump that has been drawing extra current may have eroded the relay's contact points. If the pump runs and you have spark, check fuel pressure.
FWIW sometimes electric motors decide to go to sleep, usually a shock wakes them up. I've "cured" many an electric window motor and one fuel pump by giving it a good smack. The fuel pump by banging HARD on the fuel tank.
Good luck

[Binjammin]

If you're going to follow Spirit of Bavaria's advice, direct the fuel flow into a jar, please don't spray fuel all over your engine. There's no need for that kind of risky behavior.

Also, is this what you're talking about?


The gold colored part on the top isn't a pressure regulator, it's a baffle to reduce the fuel pulses. Some models of e34 and e34 had them, some didn't. The fuel pressure is unaffected by its presence. Check your fuel pressure, it's been a few years but I believe an e34 is supposed to have 52 psi +/-2 psi. Double check that though, my memory can easily be slipping.

Also, you can usually buy spark testers from harbor freight for short money, I think I got mine for $20 or $30 for the kit.

http://www.harborfreight.com/inline-...ker-69014.html

Kit will come with parts like that, mine came with the adapters for deep plug heads and other bits.

[SpiritofBavaria]

Does it run with the starting fluid? It would be an odd coincidence but there could be other faults. Ign.?
How did you test the pump? Because the relay is clicking doesn't mean it's making good contact, a failing pump that has been drawing extra current may have eroded the relay's contact points. If the pump runs and you have spark, check fuel pressure.
FWIW sometimes electric motors decide to go to sleep, usually a shock wakes them up. I've "cured" many an electric window motor and one fuel pump by giving it a good smack. The fuel pump by banging HARD on the fuel tank.
Good luck

You must have missed the part where he says he put in a new fuel pump, confirming that his old one was dead.

[5mall5nail5]

Common E34 no-start problems.

1. Fuel pump.
2. Fuel pump relay.
3. Crankshaft position sensor.

All these things must be changed when you first buy the car. Don't wait till you get stuck somewhere. Towing and emergency repair charges are not worth it for such known issues. Oem parts for these three are under $250 shipped, so its cheap.

Dude please stop. Just stop.

[SpiritofBavaria]

Dude please stop. Just stop.

I'm assuming that you're buying the car from an average joe on craiglist. If you're buying it from a forummer, then you don't need to worry. They've already been taken care of.

Of the three common problems, I've had 2 happen to me. Of the several uncommon problems, I've had 1 happen to me (starter). My car is my DD, and I treat it as such. Anticipatory replacements, good consistent maintenance, good reading and car buddies both online and offline and asking questions, a copy of the Bentley manual, are all needed for you to efficiently maintain your vehicle without burning a hole in your pocket. We all know that we can't just trust workshops, and we all know that we can't always trust the dealer and anyway its very expensive.

The three common problems WILL happen to this car. Its a done deal. In 90% of cases, it happens without forewarning. It can happen anytime, anywhere. It will ruin your day, especially when you know that you should have fixed it after reading all the threads out here involving this. You can pay for towing and mileage with a tow company. You can do the repair yourself, after waiting for the parts to arrive by mail. You can see how long your luck holds out.

Its your choice, but not everyone who buys a cheap car is on welfare. $250-$300 to bulletproof your vehicle (add another $150 for essential cooling system components, and 3 hours of labour if you're not doing your own work), is very small beer.

[whiskychaser]

I think that is 4 votes for checking the fuel pressure?

OP, if you go down the flow route then at least record the time the pump runs and how much you collect in a jar. Stats are in Bentleys. Incidentally, if you jumper the fuel pump relay on a good system, fuel will flow. Even if you have the key in your pocket.

Thanks to Binjammin and Ross I learned two new things today - there are different sorts of pumps and I need a bigger hammer

[ross1]

I think that is 4 votes for checking the fuel pressure?

OP, if you go down the flow route then at least record the time the pump runs and how much you collect in a jar. Stats are in Bentleys. Incidentally, if you jumper the fuel pump relay on a good system, fuel will flow. Even if you have the key in your pocket.

Thanks to Binjammin and Ross I learned two new things today - there are different sorts of pumps and I need a bigger hammer

The pumps are same. The pulse dampener can be removed and the regular banjo bolt used to hold the fitting.
You can never have too big a hammer. My point was that even a new pump can be "duff" out of the box.

[whiskychaser]

The pumps are same. The pulse dampener can be removed and the regular banjo bolt used to hold the fitting.
You can never have too big a hammer. My point was that even a new pump can be "duff" out of the box.

I didnt know the pumps were the same so thats another thing I learned today. I did know you can get duff pumps out of the box - I bought a Lucas one once. I have made an appointment at Paul's Tool Emporium (it does exist) to view some hammers.

[gtopaul]

Rare E34 no-start problems.

1. Damaged DME. Crank but no start.
2. Busted fuses for the central locking system (?) under the back seat.

Check the fuses, have spares handy, and have a spare non-ews dme ready (if your car has an EWS2 system).

Actually had a weird problem with this no start situation last week and again yesterday at a gas station. Everything running fine with no problems, shut the car off, come out a few minutes later and it just spins over. I did get a 'Trans Program' light at the same time. After rooting around under the back seat I banged the relay Module and the car started right up so I bought another Relay module off ebay and installed it and everything was good until yesterday at the gas station and it just spins over again after getting gas. I popped the back seat out and banged the Relay Module and it started right up again. Later last night my door looks and interior lights stopped working so today I pulled it all apart again, pulled the GM and Relay modules out and cleaned the contacts with electrical contact cleaner spray, same result. All fuses look fine. Finally decided to reach underneath the two fuses for the locking system adjacent to the Relay module and 'click' everything came back alive. Door locks working, interior lights, and the car starts. Maybe just a loose connection under the fuse recepticle for the door locks and it all goes through Relay module and GM. Funny it showed the 'Trans Program' light though but if you look at a schematic just about anything can make that come on. Anyway the cars running perfectly now and if it does it again I'll completely tear all that apart and check each connector.

[upallnight]

You could have gotten the fuel lines mix up so the feed is now the return and the return is now the feed.
Or if you had to install new wiring connectors to the pump, you might have gotten the + side mix up with the - sign.

Seen both of these problems on this forum when inexperience owners went to replace a fuel pump.