I recently purchased a 1991 . as I was driving it back home 150 miles I noticed a few odd things ;
1.Tach works on start up but then goes to zero
2.speedometer flashes off and on usually when i hit rough spots in the road( oddometer adds miles even when it is not visable)
3.power seats do not work
the car stared and drove fine with plenty of power so i assumed these to be minor electrical problems

last friday I put a bottle of lucas oil injector cleaner in the tank and added 10 gallons of gas i am assuming the gas gauge is working properly and it shows 3/4 full .saturday morning i took it out for about a 50 mile drive i stopped for 30 minutes or so and when I got back in it it stalled almost like running out of fuel. I got it started and put more gas in thinking gas gauge was not right . started fine pulled out on road and it stalled .started back but no power stalled again did this a few times until it got to a point it would not start at all . had to be towed home
a friend says tap on the tank and pump might start working .I did this and now it starts fine and seems to have power although i have not driven it. I bought a new fuel filter and will change that today as it looks like the original is still on the car with 89000 miles LOL
could this be a problem caused by the injector cleaner ,fuel filter or even a failing pump or with the electrical problems could it be a bad BCM or ECM .would those start working again after they caused the car to stop?

 

Re items 1 & 2, this might be a poor ground. These systems work on pretty low voltages. Suggest your next purchase be a Factory Service Manual for wiring diagrams and a multitude of other things for the future.

When you turn the key to "run" you should hear the fuel pump whine for a couple of seconds. Leave the key in "run" briefly before each time you start the car to see if you hear the pump. If you hear nothing and the car does not start, the pump is not working.

And finally...Hope you enjoy your new ride.

 

Last Friday, you put snake oil in your tank, IMO. Lets start with the first thing. Get a fuel pressure gauge and check the fuel pressure on the fuel rail. It should be a tire valve stem looking thing on the fuel rail. When you turn the key on, it should cycle the pump and pressurize the fuel rail. Next, watch the gauge after turning the key off and seeing how fast it falls to 0.

With the engine idling, remove the vacuum hose from the fuel pressure regulator and see what it comes to.

Replace vacuum line and go for a drive. See what the pressure at WOT is.

After that, you can make sure you have 12V going to the pump. See if you can hook up a DVOM and run it into the car and drive it for a bit.

 

Well I have found a few things . First the ground strap going from the frame to the bell housing was broken , I hope this might help with the instrument cluster problems but as for the no start I emailed Jon at FIC and he told me the coils of multec injectors are wet so I figured the injector cleaner deteriorated the windings . I Ohmed them and found two at .004 the other 6 were all around .015 so unplugged the two bad ones and it started . At least I know the problem now . So I am ordering a set of bosch III from FIC

 

If the ground does'nt help cluster remove and spray electrical cleaner on plug.