Hi Im new to these forums. I am an ex-DSM driver and now have a 5000 cs.
So here is my problem. My fuel pump was making a horrible racket and it sputtered briefly on me once at a stop light, BUT it drove into my garage. Then I ordered a new bosch replacement. the swap went smooth, no alterations needed. But now the car won't start. I checked spark, its good. When i turn on the key the pump stays on, rather than building pressure and stopping. It has fuel past the filter but not after the fuel distributer. I put the old one back in and it started if only briefly. Doesn't this sound like a DOA part? or am i missing something.

P.S. my Diehard battery has turned this thing over a whole bunch of times and is still running strong, sorry im just shocked.

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It might be air in the system. CIS can be a real pain to bleed and running the pump doesn't help and will only destroy your new pump. What you probably have is air in the rotary rollers inside the pump. High pressure fuel pumps are not able to pull vacuum like a diaphragms pump. You can try using a big syringe to suck in some fuel through the fuel fitting at the filter. You don’t need to suck in too much fuel just enough to get to the rotary vanes.

 

You most likely have a bad check valve. The check valve is mounted on the end of the fuel pump and it's purpose is to stop the fuel from returning to the tank when the pump is pressureized. A new check valve is not included when you purchase a pump, it's sold seperately. When the check valve goes bad, the pump continues to run and the fuel pressure cannot build up to the required 90psi. Doing a simple pressure test on the car will tell you if the check valve is maintaining the fuel pressure.

Graymarki

 

I have an extra check valve so i will check that out next, because its easy. I almost replaced it on principle before but didn't think it could help. I appreciate the responses and will keep you updated.

 

i replaced the check valve on the new pump and it still would not even try to start. For a pressure test i would probably just need to insert a T connection and attach a pressure gauge, is that correct?
so, to offramp:
where would i squirt the fuel into with the syringe? from the filter under the hood or the filter screen on the bottom of the pump?

thanks again for the help I don't have a manual yet, this was supposed to be cut and dry.

 

IMO I doubt that it is the check valve.

Is the tank full?

I don't think that you can effectively prime the pump out of the tank. The syringe is just a possible suggestion to try to draw in some fuel from the fuel tank through the pump and out the fitting and into the syringe. I wouldn't try to use the syringe to force the fuel back in. You will probably have to fabricate something as all the fittings are threaded so getting a good seal is not going to be easy.

I once had to prime the fuel pump on my 1978 SAAB also equipped with CIS injection. What I had to do is something that I do not recommend. I had to loosen the banjo bolt on the pump connecting the fuel line then briefly turn on the pump until fuel started shooting out. Obviously a fire hazard, but this bled the air and everything worked fine.

A "T" and 100psi gauge is enough to test the fuel pressure but a CIS pressure tester is the best way to go. CIS works with pressures as high as 90PSI so you will need some serious connectors and FI rated hose.

 

Here is a diagram of the fuel system. Disconnect the inlet line coming from the fuel filter to the fuel distributor, then turn the pump on to see if your getting fuel to the fuel distributor and there are no obstructions. I know that this is a four cylinder diagram, but the five is basically the same. This connection is where I always do a fuel pressure test.

graymarki




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OK so I got a new fuel pump and put it in. It didn't help so I started poking around in the engine bay. I unplugged and cleaned the electrical connection on the warm up valve (attached to the engine block, two gas connections, with two wires at a connection) when i connected it again the engine almost started, (before it wouldn't even try) So to make it short, If i reconnect the warm up valve it tries to start then quits trying.
I've tried bleeding it at the pump, and checked all connections.

 

Did you try puling out the injectors and lifting air flow sensor plate to see if you have fuel coming out of the injectors? I think that system pressure check would be a good idea.

 

OK so I bought a new fuel pump and installed it. But when I cranked the motor over a couple of times it still did not start or even try to start. so i gave up and towed it to the shop. they promptly started it right up!!!!
So after all is said and done here is the analysis.

the old fuel pump was bad
the first replacement must have been bad, DOA
the second replacement (a master fuel pump) worked,
When you replace a fuel pump you have to crank on the motor at least 15 times to build pressure in the system, especially after pulling off all the connections I pulled off.
I did that with the first replacement but did not do it on the second, figuring it was something I had missed somewhere else in the system.

the car is up and running strong. I have driven it several times since.
thanks to all the responses and help.

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