• Hi Guest!
    You can help ensure that British Car Forum (BCF) continues to provide a great place to engage in the British car hobby! If you find BCF a beneficial community, please consider supporting our efforts with a subscription.
    There are some perks with a member upgrade!
    **Upgrade Now**
    (PS: Subscribers don't see this gawd-aweful banner
Tips
Tips

no start problem

Share this page

8

84jag

Member
Offline
ok,guy's.got no power to the fuel pump,but it works with jumper wire.fuel pump relay is good and pump works with jumper wire from battery..gas is getting to injectors.when the key is turned i don't hear the fuelpump or injectors.white/green wire going to fuel pump has no power.is it possible the inertia swich is bad. working on a 84 jag xj6.thank's
 
What Model and Year of Jag are we discussing?

There can be a number of reasons for the problem, which are dependent on Model & Year.
 
ok,got my ignition switch harness today,got a problem.went to plug in the part that goes to the back of the switch,but the metal piece needs to come out.do you know how it's held in.i got the harness part out.the part that wraps around the harness is still connected.
 
Is it a fuel problem or an injector problem? There is a fuel pump relay gizmo on the firewall; it is red and says "Pektron." Don't forget that the pump needs a good ground as well as power.
 
i believe it is an injector problem,running a wire to the pump just trying to start it,got gas in the fuel rail but do not hear the injectors.got a new fuel pump relay 3rd one over on the firewall,the 1st one is a red relay according to my book is a diode.you think that might be it.the book doe's not show a efi relay.
 
The injectors are powered through a pair of power transistors (if I remember correctly; I'm out of town and don't have access to my books) and then grounded through the computer. Make sure the computer has a good solid ground or it won't work. If you have or can find a "noid" light you can test the pigtail to the injectors for signal.
 
ok,thank's,i'm going to look for those transisters and get a noid light.the computer is grounded well.first thing i did was check all ground's,learned my lesson on a 280zx no start problem.i think she will start if i can get the injectors to go.
 
I believe that there are two fuel system relays. If your car came with the owner's manual and the fancy binder for the glove box, there should be a set of wiring diagrams on a folded sheet of paper in the binder. The fuel system diagram will help you match the color coding for the two relays. One wire is pink with black stripes. One relay has at least one wire that connects to the EFI ECU in the trunk and runs the pump. So, there should be a Main Relay metal with a Bosch P/N and a Pump Relay that looks almost identical but has a different part number.

The injector harness should connect to a "Power Resistor" which will be about 4" long, 2" wide and about 3/4 inch thick It will be mounted somewhere under the bonnet. The injector harness plugs into it. It splits up the injectors to determine which will open and close when.
 
look at my updated post under wheres the efi relay.i found the power resister which has a wire coming from it to nowhere.is it possible this is the power wire that's missing on the coil.i've got 3 grounds and 1 possitive connected on the coil.there were no wiring diagrams in my book.so i'm trying to use my haynes and this site to get it running.i think it's a brown with black stripe wire.also is the diode relay supposed to click when trying to start the car.
 
ok.i have 5 wires total going to the coil.the fuel pump work's now thru the switch.the injectors have power and i have spark,still no start.not even trying to start,it will turnover.i do have fresh gas in the tank's.anything else to try.
 
Well you know the old shadetree trick is to put a bit of raw fuel in each cylinder and crank it, will surely let you know if fuel flow is the prob. Just a bit now please.

We use to use a coke bottle and dump it right down the carb and stand back. Look maw no eyebrows.
 
There are two relays side by side on the firewall. One is the main relay and the other is exclusive for the fuel pump.

Check in the owners manual binder. My 87 has a large folded sheet of wiring diagrams. You should be able to determine which of the two bosch relays is for the fuel pump from the wiring color codes on the diagram.

The fuel pump relay gets part of the signal to close from the EFI relay.
 
I'm going to suggest ruling out ignition and verifying fuel


If you look at how the injectors are mounted, each has a bracket with two threaded studs with nuts holding the injector in place. Pick the easiest to get at, remove the nuts and pull the bracket back so that you can pull the injector loose. There is a small rubber seal where it seats against the intake manifold. Make sure the seal is not lost. Insert the injector with the fuel hose and wiring still attached into a mayonaise jar with a 3/8" hole in the cover by inserting the tip into the hole. Have someone turn the engine over briefly.

Does fuel spray from the injector?
 
Back
Top