hello everyone I am new to the forum and I have ahead scratcher. I have an 89 F150 with a 302 and dual tanks. I had a bad cam sensor so I replaced the distibutor. truck ran but would starve itself of fuel on acceleration. Had aleredy replaced low pressure pumps, so I had low fuel pressure and replaced high pressure pump. started and made i half way out of shop and died. Now I have no power to pumps. replaced fuel pump relay. have 12 volts in adn out of relay. only 9 volts to inertia swith ( tests fine) and no pwr to pumps. wire ohm fine. not sure if fuel pwr would go through igniton module adn it xould have fried? Anyone have any other ideas?

 

I went back out and verified a had spark so the module is good I think. I also bench checked high pressur pump. its good. if i ground the system to run all pumps all the time I get nothing. Maybe i should start running new wires?

 

Up on the core support just in front of the negitive battery cable, check and clean those grounds. Also, if it was starving of fuel on takeoff check your fuel pressure regulator, and make sure the vacuum line to it is good.

 

checked grounds and they were fine also cecked line it was fine also. Sprayed a little fuel in intake to make sure it was only a fuel problem. Didnt start. turned over like out of time. Moved distributer and fuel pump relay clicked. So maybe ignition module and pump relay connected? going to pull it back up on #1 and restab distributer.

 

Jump #6 to #2 if your pumps run your relay is good. this will keep them on all the time. try starting the truck.

 

tried jumping and I still get no power to pumps tried it with old relay and new relay. Re installed dist. and nothing. Cranking like batt is dead but show 12.5 volts. Will try new battery when I go back. What would cause power drop between relay and inertia switch?

 

Corrosion on your firewall connector where the connection passes through. Follow the wire between the relay and inertia switch and you'll find your problem.

Adrianspeeder

 

Went out and verified spark this morning. (waited for blizzard to pass) Strange that it will not fire with fuel sprayed into intake. Going to go out this afternoon and trace wires. Thanks for the help so far.

 

wait, now you're not getting fire?

 

I am getting spark, but will not start if I spray fuel in intake. Brought it back up on #1 and verified timing. Whats wierd is it was starting and runing fine untill I lost pwr to pumps. Did find melted connector at fuel relay. Repaired it and have same proplem. 12 volts into relay 12 volts out of relay, but only 8 to 9 volts at inertia switch. Starting to wonder if its in the computer? but everything else seems to be working. Only things I have replaced is distributer assembley (new cap, rotor, and module) and high pressure pump right before problem. Initial problem was no tach input (cam sensor) and low fuel pressure at rail (high pressure pump) Replaced both fired right up Idle down after warming up put inot gear went 10 feet and died. No pwr to fuel system. Replaced entire plug end on fuel relay and new relay were burnt. I am just stumped and am going to try testing wires utill I find spot were voltage drops.

 

now its getting stranger the relays are not closing when I turn on the key. If I ground the fuel pump relay it will close. Had 12 volts to inertia switch but 0 out. Pulled inertia switch and tested continuity nothing. thinking the switch is bad. tried bypassing inertia switch to see if the pumps would run and nothing. bench checkd pump worked. I have decided electrical issues will drive you crazy.

 

maybe your starter switch is bad?

 

I'll check the switch, but probably not till the weekend. I wont have time untill then. thanks for the help

 

traced the problem to the inertia switch. Wondering if the electric fuel pump slid out of protected wrap and shorted on mount causing the relay and the inertia switch to both melt? Also noticed the relays only close when distributor is in certan positon. Any one have any idea what would cause that. going to try to find a salvaged inertia switch tomarrow and rewrap the pump before I try again. Wish me luck!

 

OK I am about ready to sell her. I fixed what I thought was the problem. After replacing the inertia switch and wrapping the pump so it no longer grounded she fired right up. Was going to let it warm to set my timing and she died. Have fuel pressure have spark. It will start and only run for about 15 seconds. I checked codes and got a code 18. I have a new distributer, all new fuel pumps, and new fuel relay. I did try another coil and no change. Had my wife start the truck, while it was running I unpluged the map vacuum line and the truck ran untill I pugged it back in. When the truck was running if I tried to accelerate it would die. Is there a way to check the map sensor, and would that couse the truck to miss durring accelreration? I feel like I keep checking the same things. Is that considered insanity?