CWO4Mann

ULPilot, really the only way I can see to properly test the fuel pump is to remove it from the vehicle and do something like what I did. Read Jim Bailey's words again and do not run the pump dry. It is a liquid cooled by the circulating gasoline. Don't try to do the circular pumping test with gasoline -- it is too dangerous. Use a fluid which has a much higher ignition point, diesel for example, or for a very (10 seconds or less) test, you can squirt the insides full of WD40 and see what happens when you apply voltage to the terminals. If the pump is seized you will get a clunk sound with a hard torque movement. If that happens, reverse the terminals and try it again. Don't leave it connected to the power after you hear the clunk because that means the pump is not rotating inside the housing. If you have pressure air, you can try blowing it out, which is what I did, using 150 lbs air in one side and out the other and reversing several times. That did get some small chips out. If all of that fails, you might just try submerging the pump in a 1 gallon bucket of kerosene or solvent for a couple of weeks to soften things up inside.

Believe me, when I first heard the "thunk" of a dead pump I was hoping I wouldn't have to spring for a new pump. So far so good ....

Cheers,

ULpilot

You explained the thunk I was getting perfectly. I had heard about the not running it dry earlier, so didn't put it on for more than a second at the time. A good knock, lots of WD40 sprayed, then running it back and forth a little bit seemed to loosen it up. It's back in now and today I'm happy to report that the car ran for the first time in years. Pretty rough for a minute or two, and it took it forever to catch the first time (I'm assuming becuase it was not run for so long, and it was completely dry in the lines). But it starts up quickly now, and runs pretty well (we'll see if that is true when I can run it for a reasonable amount of time, just a very short test today due to the rad leak).
Thanks again to all for the help,
Simon

CWO4Mann

As I learned from the Army --- when all else fails, use a bigger hammer!

Cheers!

ULpilot

So the fuel pump was working alright after that for a few weeks (several starts). But now the car won't start and I am quite positive that the fuel pump isn't running (can't hear it). If I bridge the relay, it runs fine. So I changed the relay with the starter relay (I know this relay is good)- it didn't work, so I changed it with the blower relay- and it still didn't work. So... if it works fine when bridged but it doesn't seem the relay, what's going on? Some sensore thinking that there is a problem? Oh yeah, I forgot to mention- I tried it with the battery fully recharged, and then with another battery charged... still nothing.
Thanks,
Simon

Jim bailey - 928 International

Bridge the relay so the pump runs and then try to start the car. Crank it a while then pull a spark plug to see if it is wet with fuel. Spark fuel compression that is ALL you need...

Bill Ball

If I am reading this correctly, it runs fine if you bridge 30-87 on the fuel pump relay socket, but not with a swapped good relay. That points to a lack of ignition signal to the fuel pump relay. Jim or somebody else can take it from there.

Jim bailey - 928 International

Thanks Bill I see he did state that it runs when jumped that probably indicates an LH brain failure since the fuel pump relay is controlled by the brain . Try another LH Brain... that is a classic LH failure mode no signal to the fuel pump relay.

ULpilot

oh...(word of your choice here)
Any way I can test for this? I don't have another LH brain sitting around, and can't really afford one at the time. Are there some other tests I can do to be absolutely sure this is it?

Bill Ball

Crap. I was worried that might be it.

ULpilot

Sorry to keep beating this really old post.
I tried it again today- bridged the fuel pump, and the fuel pump does run when I do that. But the car DOES NOT run. Normally it has some trouble starting, but I'm pretty sure it will not run, although the fuel pump is going. Is this proving that it is the LH brain?
I have been assuming that the fuel pump is not running when I turn the car over because I haven't heard it. And usually it is spinning for a second or 2 after I stop turning the engine over.
What does the LH brain control besides fuel pump...injection, everything? :-(

So- if it is the LH brain, anyone (in Central New York) have a brain I could try... or ugh... buy (at an impossibly low price)?
-Simon

Jim bailey - 928 International

There are numerous things which could keep the LH brain from triggering the fuel pump even as simple as a bad relay for the brain ....12 th one from the left top row swap in a known good 53 relay

RngTrtl

Maybe I am missing something here, but it sounds like to me that there is probably some crap in the fuel lines that is blocking the flow. If it were me, I would get a FP gauge and hook it up to the fuel rail to see if you have pressure. If so then hook up a piece of fuel hose to the fuel rail and into a container to check flow. This is what I did and come to find out I had crap in the lines... amd all of these symptoms. Remember that you are playing with gasoline while you are doing this so keep a fire extinguisher handy and use the buddy system if you try this test. Granted there might be other issues, but knowing that there is flow to the fuel rail and back would be helpfull to have b/c no matter what the problem is, no fuel flow = no gonna work.

Bill Ball

Your symptoms are changing. Previously you said it started and ran fine with a bridged pump relay but not with a good pump relay. That pointed to the LH signal to the fuel pump relay, as Jim pointed out. Now, it doesn't start with the pump relay bridged. Of course, the pump is suspect based on its condition prior to dropping it off the table. The LH is still suspect as it controls the injectors as well the fuel pump signal. EZK (ignition) could be involved. You need to replace or jump the EZK relay too as a diagnostic test. I usually jump them all. If the car runs, then start by removing the EZK relay jumper, etc.

ULpilot

Sorry to not be clear earlier. I meant the fuel pump ran fine when I jumped it. I didn't get the car to start, but I didn't try a lot then. I didn't realize it was ok to run the car with the relay bridged. So, pump works when bridged, but car doesn't start. Might be another unrelated problem, but I'm hoping not. I'll try what you suggested tomorrow and let you know. Maybe there is still hope!

Bill Ball

OH! Big difference.