I just had a new fuel pump installed in my 98 discovery, along with two ignition coils, new plugs and wires, and the fuel filter for good measure. Everything went in fine, but here's where things get weird.

Now the fuel injectors are getting power, but aren't grounding. The truck will run when it's sprayed with fuel, but it otherwise it just cranks. We've checked the inertia switch, the crank sensor, computer swap (which had some corrosion on the case, but it wasn't bad) and we're about to check the cam sensor. After this, we're running out of ideas. I think it might be a ground issue, but wouldnt know where to look. Any help would be appreciated!

 

See attached pages from RAVE, multi function relay, etc. But ECU supplies the ground to each injector, so it may be toast as well.

 

If it runs when sprayed with fuel, it's likely the fuel pump isn't pumping.

When you pulled the ECU and swapped them, you may have lost alarm sync.

Spark? Fuel pressure?

 

I wonder if they don't need the AS10 as well from the donor of the ECU. Mine wouldn't start without the AS10 from the donor, I tried to short cut it to see if my buddy Tim the Enchanter was correct. Started up after the donor AS10 was plugged in. AFAIK the two are factory code mated with the trucks VIN and can be mated at the dealer after a swap of one or the other. I dunno. Both Tim and SB didn't mate them and had no issues. By the way, good to see you here PT, more D1 action than you could shake a TC lever at. Spike should add you as a mod.......

 

I never told my ECU and 10AS they were adopted.

Are you getting a CEL light in key position II? If not perhaps the ECU and 10AS are feuding. Did you have the battery disconnected while swapping the pump? If you did and failed to depress the hood switch when you put the cable back on you probably armed the alarm.

 

How about a fuel pressure test on the test valve on the passenger side fuel rail. Even without cranking that should pop up in position 2. MFR should run pump for a short period (seconds).

 

I only swapped the computer for about an hour, because it wouldn't crank at all, so I put the old one back in. I'm afraid that by doing so I armed the system but the key fob is still calibrated and working. In regards to having the battery disconnected while swapping the pump I'd have to ask my mechanic, I didn't do that myself. Right now the fuel pump has been bypassed at the inertia switch with a toggle, because the multi function relay was acting ...strange. Everything inside (lights, chimes in pos II, stereo) is working fine. Tomorrow I'm going to double check the grounds on the injectors and see if I missed something. Thanks everyone for the fast replies!

 

I was told by rover that the security system will cut the starter motor, not the injectors. If need be, I'll try using everyones suggestions to get the computer to cooperate and play nice, or replace the MFR.

 

Do you have noid lights? If not, how do you know the injectors are getting power but no pulse?

 

You can use your trusty test light to check for injector pulse.