It just clicks on and off rapidly when i turn the key. the light on the MS blinks with the fuel relay. i'm thinking i'm not getting a good ground but i was told the fuel relay is grounded through the MS. i have all my grounds going to one point on the frame and from there it attatches to the transmission.
now here is where it gets a little odd. if i turn the key and just let it click and i jump the ground wire to pin 86 (ground) on the FP relay the light comes on but very fient and the fuel pump turns on and the clicking stops.
this is really killing me because my MKIII is not running right now and i''m trying to get my MKII going so i can drive to work and whatnot.
all i did was replace the wiring harness because the old MS harness worked but was a little ugly. and now something is messing up.
here's the diagram i'm using. see how pin 86 only goes to the fuel pump wire on the megasquirt.
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the operation of most fuel pumps is controlled by the fuel pressure regulator
when the fuel pump gets to set pressure , the pump is switched of by the ECM at the relay level
maybe nothing wrong with your system just the system working as designed
if you have pressure in the fuel manifold when you turn the ignition on then the pump will not run but will if there is a fuel leak somewhere and the pressure drops off
If you have no fuel pressure at the engine when key is on, the pump is not coming on. Check fuel pump fuse, check fuel pump relay (relay should click when key turned to on-put finger lightly on it and feel for click when someone turns key to on). If no click, signal from computer may be lost, ground for relay may be lost, or relay may be bad. If it clicks, wiring from relay to pump may have failed, or the relay's main power source may not be there at relay-find the fuse link or maxi-fuse that powers that relay. One terminal at relay should be hot at all times-can check for that with a test light. If pump is working and you do have fuel pressure, you will need to check injector circuit. Post back if questions, or need further help.
My 1992 Cummins W250 auto trans turned out to be the Computer/ECM mounted on front fender by battery tray. Mine only acted up in cold wheather. It started out with the ASD (auto shut down relay) clicking rapidly. In addition the water in fuel, wait to start and check engine light also blinked fast. In this state, the battery would not charge.
possible fuel pump shorting out problem, disconnect fuel pump wiring connector located around tank area under vehicle & turn key on again. if no more clicking from relay or theft warning stops. then change fuel pump, and check the short wiring harness to fuel pump for overheat signs.
If the fuse is becoming quite hot, the problem likely lives in the pump motor itself. Replace the fuel and relay together to avoid any further issues. Fuel pressure is critical on these models, so please heed to caution when buying one aftermarket.
fuel pump relay is in engine compartment on drivers side under the flap the two relays that are together ,it is the bottom relay,,u cant by pass.if relay is good ,if it clicks when turning over and key on and off (it should click and go off if key is turned on) then use a test light and ground it find wires going to top of tank and probe wire have some one turn key on ,it should light up test light and go off ,if this happens ,replace fuel pump