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My friend's Aerostar won't start. Itr acts like fuel not getting to the engine. He says new fuel filter. Is there a fuse for the fuel pump? Or a relay? I assume there is because every car I ever owned has it. But I can't find it. I looked in the car interior and find the fuse box for the lights etc. I look uder the hood and cannot find it. Anyone know where it is. I am now going to help him. Firsat I'll listen for the fuel pump. I am assuming it's in the tank.
Any suggestions? Thanks  

hmm...   do you have a rubber mallet???   you can pound hard on the bottom of the gas tank.. While somebody cranks the engine..

this will usually get the fuel pump to spin ONE more time..    no guarantees..

fuel pumps are brush type motors..  when the fuel filters clog.. the fuel pump works harder needing more amperage to spin the motor.. this is more than the tiny brushes were designed for.. they burn away.. scoring the commutator..  until one brush does not touch.. .. sometimes the rubber hammer on the bottom of the tank HARD will get the pump to spin..


you did not mention if its a 3.0 or 4.0..

this is the wiring diagram for a 3.0... the 4.0 is similar..



pay close attention to the upper left corner of this diagram.

find the pink and black stripe wire that plugs into the inertia switch..   see if you get power on one of those when cranking.. that shows that the fuel pump and the EFI main relay are working properly...

be sure to depress and release the button or bar on the inertia switch.. and verify that the power passes through.. properly.. once in a GREAT while.. the inertia switch contacts will fail.. usually when the fuel pump is drawing massive amounts of amperage as its dying..  

oh... i have also had problems with the ignition switches ... i have actually had the white plastic bottom fall out of these..



there are several strong springs pushing the contacts against the plastic plate..  the only thing holding the plastic  plate in is the LITTLE 4 fingers slightly bent over the ends..




as for the fuel pump.. there are 2 options..  one that is just the pump.. and then you put the new strainer on the bottom..



this is the strainer that gets pushed on the bottom of the new fuel pump.. failure to install this.. and failure to purchase this on the same receipt you buy the fuel pump on will void any warrantee now a days..  

 

the pump won't last if you don't install one of these anyway..

the other is a complete pump and hanger assembly .. with a fuel level sending unit..   after 22 years.. this complete assembly is usually the way to go..

please.. use extreme care when dropping the tank.. the fuel lines are plastic.. and easily broken..  

Strangest thing. He fixed it. It was a vacuum hose that broke?  

It's not fixed. It was coincident. Seems his fuel pump MAY be bad. Now to figure out if it is bad.  

monitor the fuel pump amp draw with a harbor freight circuit tester..



there are 2 versions .. one for conventional sized fuses.. and one of the tiny sized fuses used on newer cars...

20 Amp Automotive Fuse Circuit Tester  ITEM # 67725




30 Amp Automotive Fuse Circuit Tester ITEM # 67724   either one is 15 bucks when not on sale...

plug it into the fuel pump fuse location... then the removed fuse into the side of the unit.. . then monitor the amp draw...


you could also have a failing.. inertia switch... or a failing.. EFI main relay.. or a failing fuel pump relay... also a bad ignition switch... where the contacts have overheated and the switch shows signs of melting where the wires plug in..

a normal fuel pump should draw while the engine is running.. 6.8 to 7.5 amps.. and be a steady draw.. not increasing in amp draw  

if you look at the diagram above... you will see the fuel pump and other circuits are powered via fusible links...

these might just be fuses.. or maxi fuses..


does the fuse box cover still exist???   to identify the exact location of the fuel pump circuit fuse..

can you also verify that you are getting switched power at the red and light green stripped wire at the main relay...  the main relay has 4 wires to it.. the fuel pump relay has 5 wires to it..

when the ignition switch is in the ON position and while the engine is being cranked..

you should have power on the red wire to a bunch of stuff.. the easiest to get to is the red wire on the idle air control valve..

the pink and black wire from the fuel pump relay to the inertia switch should have power ONLY for 2 seconds when you turn on the key..   while cranking.. and while running..  

PLEASE DO NOT PROBE THE TAN and light GREEN wire to the fuel pump relay..  you can damage the computer if you do so,.  

mechanics have invested in a low amp current probe/clamp..

reads from milliamps. to about 40 or 60 amps..

these can be had from several sources...   aeswave  dot com..

or the ATD tool flyer..



they do require a digital volt meter with a 200MV DC or a 2 volts DC setting..

professional mechanics have this.. and use it with a digital storage scope.. they clamp it on the fuel pump wire..  take a recording.. look at the amp draw wave forms

~~~~~~~~~~~~~~~~~~ would be a good wave form..

~~~'~~~~~'~~~~~~'~~~~~'     this would be a commutator going bad...  

there are wave forms  to know about..   but it takes an expensive digital storage scope to view it.. as you have to look at the individual draw pulses from a tiny motor spinning at 6000 RPM..  

It was a bad battery cable. Really weird. Seems one of the connections was bad. The cable to the starter was fine because the starter was cranking over and strong. But the fuel pump was not getting juice. My friend wouldn't listen to me to check everything , connections etc. I couldn't help him. He paid a shop and they charged him $200 to do the diagnosis and the work. May be a lot of $ but he's running. He's PO at me because I was telling him the fuel pump is not working and to check "Why". He'll get over it. But he's on the road again.  

Oh well...

you can lead a horse to water.. but you cannot get them to open the hood..


next time that friend comes over...   or you are over there.. ask him to help you with something and break out your digital volt meter and run the test..