Fuel pump relay connector measurement less than a volt

[Javier]

Just noticed that in your car, the B+ post is inside the box besides the pump and DME relays, see drawing 7100.0-01 figure 2 in your schematics. Guess you knew it, but!

[Cea123]

Yes, I knew that but thanks anyhow!

[genphreak]

... when I jumper 30 and 87 the fuel does come up to the rail.

Well it would need >1V to do that. What are your confirmed readings now of the FP relay and at the pump itself?

If you have fuel in the rail and the pump is proven to be working and you should be fine. Always best to test this with a fuel pressure gauge as it is common for circuit testing to be challenging. I've had the FP relay round an unexpected way, I suspect that M50 and/or M60 e34s (or perhaps just RHD ones) are all different to M20 and M30 powered cars. Is yours LHD?

Is the engine starting at all? Another thing you can have is a flooded engine if so, I found once on mine that the only way to start it was >30s hard cranking with the accelerator down wide open (WOT) the whole time, it eventually spluttered adn farted back to life. I suspect on thee that once the flood washes the walls of the chambers free of oil, compression reduces so much that the rich mix cannot combust at all.

[Cea123]

Javier,

Due to the death of an immediate family member, I haven't had an opportunity to resume the troubleshooting of my son's car, but plan to put some time into it this week. The last things that I tested were the fuel and DME relays and they checked out to be good (they click like new). But, I came across some information regarding the crankshaft position sensor (CPS), this info mentioned that the engine wouldn't start if the CPS is bad. But, as I said earlier in the thread that the engine will start momentarily when I spray some fuel directly into the throttle body. I intend to test the CPS just to be certain that its not bad.

On the other hand, just let me add that before the no start problem arose, my son's car overheated and as a result the cylinder head cracked, so my son purchased another cylinder head and had it rebuilt by a local machine shop. My son installed the cylinder and made sure that all TDC markings and VANOS adjustments were correct and manually rotated the engine two full turns to insure all was well the timing (TDC) markings. During this top-end rebuild, my son replaced the fuel pump for generally purpose, so after reassembly the initial attempt to start the engine was momentary and would only start when fuel was sprayed into the throttle body.


If you have anything else in mind that I should test, please let me know.

[Javier]

Sorry about your loss.

Your message brings a new whole story to this issue. Yes there are a lot of things that may be wrong. A wrong CPS will prevent spark and fuel pumping, guess you have spark. What about injectors, are they getting firing signals? Are all sensor properly connected? Have you any Check Engine warning? Have you confirmed already you have fuel pressure in the injectors rail when cranking the engine? First let's be sure the pump is working fine when cranking the engine with all gadgets in place. If not, let's be sure at least that DME is sending the Fuel Pump relay the signal to start the pump. As I have to presume you confirmed there were no pressure in the fuel rail when all this started.

[632 Regal]

Very sorry about your loss.

Momentary firing... This brings flashbacks of the old 850. Same situation I was chasing for half a year. In this case it was the anti theft all along. I assumed I was getting spark because it would "momentarily fire" after spraying it with starting fluid. That is what really messed my thinking up the whole time. I don't have any idea why it would fire at all because the anti theft is supposed to kill the ignition and fuel. There was no reason for the anti theft to go on but it just did and wouldn't shut off so I had to cut one small wire to make things work again.

I would second Javiers idea and make sure you have fuel pressure and second that you positively have spark when cranking.