Crank, Start, Stall

[usualdeviant]

Searched.

OK so I was on my way to work a week ago when my 1/87 325i acted as if it were running out of gas. It started fine, and drove fine, for about 50 feet. Then it happened. So I turned back, and had just enough juice to make it back to my driveway.

Naturally I thought, since I have gas, it must be the fuel pump going bad. Also, I had a random cut-out problem prior. Well crap, I have 2 fuel pumps. No problem I thought, I just disconnected the in-line fuel pump hose at the inlet and the fuel hose at the fuel line (after the filter), watched for fuel to pump from both fuel pumps as I cranked the engine. I saw fuel pumping from the in-line pump, but nothing coming out of the transfer pump. The in-line pump still had some fuel left in it. That's how it came out.

So, I replaced the transfer (in-tank) pump. Started it up and it ran rough. I reved it and it went to 2 or 3 k rpm but then died. I kept starting it and it kept dying, ever since.

As per Bentley standards, I tested a few things so far. I tested the TPS, CTS, the ICV buzzes just fine and I cleaned it a couple years ago. I read there is an electrical test for the AFM on the 4 cylinder, and not on the 6. However, if it is lying, then that test failed on my car. The flap doesn't bind though. Unfortunately I do not have a fuel pressure test kit. My next move is to unplug the return hose at the FPR and see how good it comes out. Finally, before I called it a night, I tested the ignition coil - the one ignition component I haven't replaced yet. It failed. My question on that is, how far out of spec does it have to be to cause this type of problem? My old fuel pump is bad, right?

There you have it. I couldn't go to bed without putting this on here.

EDIT:
I disconnected the vacuum hose from the FPR but no affect. Could it be the FPR?

[bmwstudent]

how did you test the coil? With an ohmmeter? If the resistance is high (out of spec) on either the primary or secondary windings it's probably bad.

[jlevie]

If the replacement transfer pump worked (fuel coming out of the inlet hose of the high pressure pump), the pump had died. The current symptoms sound like a fuel problem and the next step is to measure the rail pressure.

[usualdeviant]

yes, with an ohmmeter, both primary and secondary resistances measured a tad high. the book says if it is any higher than spec, it should be replaced. i haven't actually looked to see if the new pump was pushing fuel to the in-line pump yet, but that's because i heard the damn thing buzzing. so i figured that shouldn't be an issue. but scientifically, i should look for fuel coming out. ok well, i'll give that a shot. i really wish i had a fuel pressure gauge though.

[usualdeviant]

I don't always get shot in the eye with gasoline. But when I do, I prefer Cheveron Supreme with Techron.

First thing I did today was checked battery voltage. It was a tad low (12.45V) so I fast charged it for a bit. Just to cover my bases. Then I cranked it again just to see what would happen. A whole lot of nothing! No surprise, really. I checked the coil resistance again, just because I'm silly like that. Still a tad high. So I'm not ruling that out just yet.

Then I went on to disconnect the fuel circuit after the filter again. Cranked and watched for fuel pumping. Saw plenty. So I figured yeah, probably both pumps are doing their jobs just fine. So I put that hose back together. Next I disconnected the return hose at the FPR. Not even a drop came out! So now I know there is an issue of blockage somewhere between the filter and the FPR. Next I removed the FPR from the rail, and wah-lah! Plenty of pressure there!

So, if I'm not mistaken, and please chime in here if I am, I had a combination of a bad transfer pump and a bad fuel pressure regulator. I actually snapped a bolt in half that secures the upper timing cover to the head. And I was thinking crap, maybe that's it - maybe now the cap is too far away from the rotor on the passenger side. But, after testing the FPR, it appears that is by far the worst contributor to my ride not firing up. Far too much pressure in the rail. Far too rich. I even tested my CPS for resistance and distance from the crank sprocket and it was just fine.

Now if all that is correct, how likely is it to have a transfer pump go bad at the same time as a fuel pressure regulator? I even hit that thing with a screwdriver and a rubber mallet to try and knock its innards loose, but to no avail.

[jlevie]

yes, with an ohmmeter, both primary and secondary resistances measured a tad high. the book says if it is any higher than spec, it should be replaced. i haven't actually looked to see if the new pump was pushing fuel to the in-line pump yet, but that's because i heard the damn thing buzzing. so i figured that shouldn't be an issue. but scientifically, i should look for fuel coming out. ok well, i'll give that a shot. i really wish i had a fuel pressure gauge though.

Go to Home Depo, Lowes, etc and get a 0-60psi gauge (like used for water systems), a 1/8NPT tee, and some 1/4x1/8NPT hose barbs. Then go to an auto parts house and get a couple of feet of 5/16" fuel injection hose and some clamps. With that you can cobble up a serviceable fuel pressure gauge. You really need 5/16" hose barbs, but they are harder to find. The 1/4" barbs will work.

[usualdeviant]

That's good advice for future reference, and thanks! However, I think I've figured out the FPR as being bad since no fuel comes out the outlet anymore. Right? Not much need for a gauge if there's nothing to measure, right? But I see what you're saying. Definitely more than one way to get results.

[usualdeviant]

OK now that all that is dealt with, the car still won't fire up. So I went back to the coil. Did a spark test and it seems I'm getting a weak spark. Orange instead of blue. You can even smell fuel in the tail pipe. Anyone know if I did the fuel pump and FPR right? I mean, if no fuel is coming out, then they are bad, right? I'm pretty sure a fuel pump is supposed to pump fuel (at least when cranking or running) and I'm pretty sure a fuel pressure regulator is supposed to regulate fuel pressure (let some go back to the tank unless you are at WOT). I am pretty sure cranking doesn't demand full fuel pressure at the injectors, although I could be wrong. Someone please chime in if I am.

Also I am curious if a not-perfectly-snug ignition cap could have the potential to make a coil go bad. I know it is a 25 year old coil but, it just seems so fishy. I snapped a bolt that holds the cap close to the rotor on one side not too long ago, maybe 3 weeks ago. It ran fine for awhile. But not long.

[usualdeviant]

OK so I went and tested the primary and secondary resistance on the ignition coils at the junkyard today. Most of them were reading just about the damn same as mine is. I guess being a hot day can have an increased resistance affect or something, who knows? Anyway, I got one just to make sure, and I installed it in my car. Nothing.

I removed the cap from the rotor to inspect it visually. I scraped off minor build up on the cap terminals and put it back together. No luck. The car will start sometimes, see, but after idling a couple of seconds, it will just die.

I even had my buddy push in on my cap, where I broke the bolt, as to have better contact with the rotor. Nothing.

The only thing I can think of now is, the insulation is broken right where the wires meet the sensor end of my crankshaft position sensor. So, could it be that it is inducing interference from the coil or something? I pulled my plugs and all of them had gasoline on them. I put in my old ones, and it seemed to have the slightest affect but nothing noteworthy.

So I have a weak spark. My plugs, wires, cap & rotor, and coil are good. Safe to say. Anyone know what else to check? Otherwise I was going to pick a CPS from the junkyard next chance I get.

[jlevie]

Looks like I missed seeing a update or two, sorry.

No fuel from the FPR when cranking could mean the FPR is bad. Which would result in flooding of the engine from excessive rail pressure. Or it could mean that the high pressure pump isn't producing enough pressure or there is an obstruction in the fuel supply line. Which would starve the engine for fuel. You find out which with a pressure gauge and in this case that is the first thing to do.

[usualdeviant]

And I would be ever so inclined to test fuel pressure before and after the rail, however, I have that weak spark issue going on. All ignition components are good, I replaced them all within the last couple of years. I even inspected and tested all of them. All I didn't do was test the wires and cap and rotor, but they should be fine. So, could an improperly insulated crankshaft position sensor make it not matter what resistance that tests at? Could that be my source for weak spark?

[usualdeviant]

p.s. i swapped the FPR.

[jlevie]

After you swapped FPR's does fuel flow from the return fitting when you crank the engine? If not, there is definitely a problem with the fuel supply, probably a bad high pressure pump or perhaps a clogged filter or obstructed line. Check the rail pressure and if low compare that to the pressure at the pump outlet. Forget about spark until you solve the fuel problem.

[usualdeviant]

No. Well I tried mine, then two different used ones I got from the junkyard, and nothing comes out of them. You could be right, I might have a dying high pressure pump. I see plenty of fuel coming out of the rail while cranking though. I don't have a tester yet.

So, fuel should come out of the FPR while cranking? That's what I figured. So I have 3 FPRs that don't work? What are the odds of that?

I finally tested my cap and rotor for resistance, and they are bad, both of them. I figure it could be due to my spraying the engine with water right after breaking a timing case bolt. Not sure. But then I went back to the junkyard today looking for caps and rotors. They were all in worse shape than mine. So I grabbed a crank position sensor that was in better shape than mine. When I put it in, it seemed to run for a little while, except really really crappy. And I had to feather the throttle. It was misfiring like a mofo.

I even tested the harness to the ECU, and it tested good. When I tested my spark and found it was orange instead of blue, I had the plug grounded to the top of the engine, which is aluminum. Is that bad? Should it be a steel ground?

So confused at this time. I guess it's time to make a fuel pressure tester.

[jlevie]

No. Well I tried mine, then two different used ones I got from the junkyard, and nothing comes out of them. You could be right, I might have a dying high pressure pump. I see plenty of fuel coming out of the rail while cranking though. I don't have a tester yet.

So, fuel should come out of the FPR while cranking? That's what I figured. So I have 3 FPRs that don't work? What are the odds of that?

The odds of three FPR's being bad is pretty darned low. Get a new pump

I finally tested my cap and rotor for resistance, and they are bad, both of them. I figure it could be due to my spraying the engine with water right after breaking a timing case bolt. Not sure. But then I went back to the junkyard today looking for caps and rotors. They were all in worse shape than mine. So I grabbed a crank position sensor that was in better shape than mine. When I put it in, it seemed to run for a little while, except really really crappy. And I had to feather the throttle. It was misfiring like a mofo.

While ordering the pump, get a new distributor cap, rotor, ignition wires, and CPS. And just in case they are bad, a set of NGK ZGR5A plugs.

I even tested the harness to the ECU, and it tested good. When I tested my spark and found it was orange instead of blue, I had the plug grounded to the top of the engine, which is aluminum. Is that bad? Should it be a steel ground?

So confused at this time. I guess it's time to make a fuel pressure tester.

It doesn't matter where you ground the plug.