Well, I had bought a new fuel pump for my 84 but unfortunately, it's not running. Three things:

How do I check if the fuel pump works?
How do I check if the fuel pump is receiving power?
Is there anything else I need to be looking for?

Thanks!

 

Nice, thanks!

I guess I need to go and invest in a voltimeter now. I've never had to buy more new tools until now that I've started working on a Jag...lol!

Thanks for the help!

 

Hi Jfrog,you can test the fuel pump by grounding pin #85(orange wire) on fuel pump relay base.Its above and outboard from the battery just in font of ECU.Pump should run continuously when key is in run position.
Les
88 1/2XJ-S

 

Nosox, will this provide the same answers I need that the voltimeter would have given me? If so, sweet!

I see that there are two relays next to the ECU above the Battery. Which relay do I need to be using?

Also, I'm very new to electrical work so bare with me. Tell me if this is right:
1. I leave the positive and negative wires connected to the Fuel Pump
2. I take pin 85 (orange wire) and hold it to the bottom of the relay itself
3. Have someone turn the ignition to the #3 position

Is that right??? Sorry, as you can see, I'm really new...lol!!!

Also, if the pump runs, what exactly is the problem (i.e., relay, voltage)?

Thanks!

 

ya jfrog that's it. I had a related problem that turned out to be a short in the wiring to the ECU. I can give you details and how I fixed it if you like.
As for being new, don't worry,I'm a fumbler when it comes to electrical too.I'd be lost without all the helpful and knowledgable guys on this and other forums.In fact that test I told you about came from one of those guys.
Good luck
Les
88 1/2XJ-S

 

nosox, the step by step instructions would be great! Hopefully with those I won't end up getting a nice little battery shock...lol!

Thanks again!

 

A little battery shock won't kill you, frog....it'll simply teach you to be aware of your wires...lol.

When I test an electrical unit, I just run a couple of 14 ga wires from my battery to whatever I'm testing. That's the easiest thing for me to do.

 

OK jfrog, i will try to be as clear as i can. I assume you know where the ignition amp is on the left hand intake manifold.
Coming out of the amp are 4 wires
2 white go to coil,one white and blue feeds your tach.The 4th(white/slate) feeds the ECU and this may be where your issue is.You can try wiggling this while a helper cranks the engine to see if it tries to start.If it does we're on the right track.
You will see it has a connector about 4 inches out of the amp... open it up.You will need to carefully slice open the sleeve it's in.Then you should see a white wire and a black wire.The white wire is shielded and coming out of the shielding is a wire that's connected to the black wire with a funky looking brass piece.If that connection is not secure your car won' run at all.
Next step is to check continuity of white wire back to the ECU pin #18.(if you need a layout of pin connectors pm me and I'll send you one).
OK next,assuming you do have continuity back there you need to make sure the shielded ground from white to black is secure you may need to just make a new connection.(thats where my issue was) I soldered and taped it real good to make sure there was no contact from black to white.
Hope this helps,sorry to be so windy heheh
Les
PS ignition off except when cranking so you wont get the 12v shock

 

jfrog I've attached the ecu layout here
Les

 

Awesome, thanks guys!!

For starters, I think I'm going to go ahead and make sure the fuel pump itself works by trying to do what motormouth suggested. This seems pretty simple.

If the fuel pump runs, I'll jump right in and try my hand at nosox's suggestion. I have to admit though, it looks pretty intimidating....lol!!!

Thanks!!!!!

 

Ugh!
Okay, I found out that the fuel pump does indeed work!
Also, I have replaced both relays!
Guess what, the fuel pump still doesn't work when I turn the ignition. Any other suggestions???



Thanks guys,
Keith

 

It should run for about 3 seconds when you turn the key "on", then stop. It won't run continuously by simply turning the key "on", if that's what you are expecting.

It should also run whenever the starter is engaged and, of course, when the engine has started.

I'm coming in late here but it should to be that the circuit in the ECU that grounds the fuel pump relay isn't working. It's a fairly common problem.

Cheers
DD

 

Yeah, I figured it would kick on for a few seconds when the ignition is turned, but when I turn the ignition, the fuel pump doesn't turn on at all.

If it's the fuel pump relay ground circuit in the ECU that is the problem, where do I find that and how would I go about fixing it?

Thanks Doug!
Keith

 

Any ideas on what the problem might be???

Thanks!