Ford EFI system question

[junkyardjeff]

My 88 bronco is getting harder to start,I put a new pump in the tank but I am thinking the front pump is going bad. I put a gauge on it and the pressure only comes up to around 5 and will eventually get enough to start and gets up to around 35 and with the regulator disconnected it will go to 45,I ran it for awhile with the regulator disconnected and did see the pressure drop some. Can the regulator go bad and cause a lack of fuel problem as when they usually go bad the pressure goes too high and runs rich.

[wayne petty]

disconnect the fuel inlet line at the back of the high pressure pump out on the fuel rail...

have somebody cycle the key on for you...

see if the primary low pressure pump in the tank works...

the in tank pumps HAVE to feed low pressure as the high pressure pump does NOT build enough suction to pull the gas up...

so the SLOW build of pressure could be the in tank pumps not supplying the high pressure pump with enough fuel ..

since you replaced the in tank pump.. your high pressure pump might have been damaged by the lack of fuel being fed into it..

if you have dual tanks.. your dual tank valve could be acting up again...

[junkyardjeff]

I am getting fuel out of the pump in the tank and the same amount from the reservour,I am getting fuel out of the front pump but not as much as I thought. The front pump is also making a groaning sound now,I do not know how long it was run on just the front pump.

[wayne petty]

fuel pumps are only lubed and cooled by fuel flow.

running dry also allows them to OVERSPEED and really take a toll on the bushings and the brushes..

a groaning sound is the pump not being able to come up to speed...  if you have good power on the + and you have verified the ground side is good.. and the ground connection between the body or frame and the battery is good..

got a LONG test lead.. even a conventional set of jumper cables...    first only hooked up to the negative.. with your digital volt meter set to 20 volts DC between the black jumper cable end and the negative on the fuel pump..

should be less than 0.20 volts... thats 2/10 of a volt..

then disconnect the negative jumper cable clamp.. hook up the positive ..  measure from the positive cable clamp to the positive on the fuel pump... again.. 0.20 max voltage..

this is with the engine running if possible.. its not an accurate test if the fuel pump is NOT running..

you can also disconnect the positive pump wire.. use your digital volt meter set to 15 or 20 amps DC.. between the end of the positive jumper cable and the high pressure pump.. see if it spins faster..  this is a few seconds as there will NOT be any fuel from the in tank pump...

get an amp reading from your digital meter..

if your meter has only 10 amps DC setting.. that is barely enough... you can try it..  most of the pumps are about 6 or 7 amps...

[kb426]

If you have the eec-iv system, it's designed for 40 lbs. at the regulator all the time.

[junkyardjeff]

I just put a new front pump on it and its a little better but still not right,I still have to crank the motor to get the pressure up so I am thinking it must be in the regulator since the pressure should be up instantly. I put a new fuel filter on it before I started driving it but who knows as it could be defective too.

[rooster]

I just put a new front pump on it and its a little better but still not right,I still have to crank the motor to get the pressure up so I am thinking it must be in the regulator since the pressure should be up instantly. I put a new fuel filter on it before I started driving it but who knows as it could be defective too.

On my 88 f150 the pressure would build up with just the key in on position!

Also had 2 fuel filters! 1 inline, 1 in canister!

These things are knowen for bad relays, I took my Ford one out and replaced with a GM!
Good luck

[junkyardjeff]

All new pumps and a regulator and still low pressure,I seem to be getting good pressure after the filter as I did not get the hose all the way on and it came off quick. I am still trying to get that funky fitting off at the fuel rail to see if there is a restriction in the line,I have the tools but cant figure it out.

[kb426]

As I remember, you slide the tool into the fitting to release it. It's been 5 years since I messed with that so I may be wrong. If the system doesn't pressure up with the key turned on after a few seconds, there may be a problem with a relay. When you first turn on the key, can you here the pump run for a few seconds? Is yours an in tank system or outside? If it's external, is the sock in the tank partially plugged? If the relay is bad, I don't think it would ever pressure up. The relay has to work for key on as well as run position. The key on part only lasts a few seconds.

[wayne petty]

spring lock couplings....

release pressure from the fuel line...

or you won't be able to push the fittings together to get the tool to EXPAND the spring so you can slip the half with the tool backwards and out..


so...  push the pieces together..

slip the tool into the spring side...  push it in hard as you have to get the garter spring to expand around the sleeve part of the tool... once its expanded .. you will feel the tool slip in farther...   then holding the tool all the way in against the flair inside...   pull back on the tube with the tool on it...


its tricky...  but once you understand that the garter spring is tight around the flair on the end of the tube.. and preventing the flair from slipping out of the donut shaped device..  

push the tube in.. push the tool in and feel it expand the garter spring...   pull the tube out as the garter spring is now larger than the flair... and you have won..

i have found that i can take spray can plastic caps... cut them into a 1 inch wide strip... roll the strip all the way around the tube then trim to length.. so it wraps flat...

you can push this in to the spring lock coupling to expand the spring and extract the flaired end..  

all this because people would take the tools home every night..  or leave them in a car... drop them on somebodies head in the pit..

the fuel system... wiring diagram

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/21/dd/16/large/0996b43f8021dd16.gif

here is a link to the 87 to 96 ford full size pickups..
http://www.autozone.com:80/autozone/repairinfo/repairguide/repairGuideContent.jsp?pageId=0996b43f8038ecd6


there are TWO relays.... and a inertia switch...
the 2 relays are slightly different..
the EFI main relay DOES NOT HAVE A DIODE..
the FUEL PUMP RELAY DOES have a diode...
this is because the fuel pump relay is controlled by the ECM..


the EFI main relay comes on with the IGNITION KEY... via power on the RED and light green striped wire from the ignition switch...

the EFI main relay switched out put is a red wire.. feeds the computer on terminals. 37 and 57,  the TAD and the TAB and canister purge solenoids,   all 8 fuel injectors the red wire on the idle air bypass valve, and the EGR vacuum regulator solenoid..  but it also feeds the control coil on the fuel pump relay with positive power..    

the ECM controls the negative side of the fuel pump relay...


the fuel pump relay output wire is brown..   it feeds the inertia switch.. becomes pink and black from there..  feeds the inline high pressure pump.. and the front or rear  in tank pumps if you have two tanks..

i don't know if this helps or hurts..

i can colorize the wiring diagram in about half an hour later tonight if you drop me a PM.. with an email to send it back to....

makes it a LOT easier to read.. as i only have to do the circuits that you are having trouble with...

[rooster]

You might want to bookmark this site, hes got alot of great stuff for Bronco's!

Here is 1 of his links, about the relays.
http://www.supermotors.net/registry/media/507187

[rooster]

I'm starting to think the duel resavar canister on the frame rail, if it not operating right it could rob some of your PSI. I think you have 2 tanks! Ever notice strange fuel readings? Like the front pump is supplying fuel to the rear tank!

You could by-pass the canister, with 1 tank and go directly to the fitting leading to the frame rail pump, you will need a extra fuel filter to do this.

[junkyardjeff]

It got to the point of no pressure but I hate to admit what it was but will tell how I found out,when I pulled the tank to replace the pump I found the wires were smashed from the factory in between the skid plate and frame but did not repair the wires. Since I was checking everything I decided to cut out the smashed section of wires,before I done that the gauge was showing over 1/8 tank and when I got done it was below E so I ran it out of gas.  Even with all new pumps and a regulator it still takes a couple cycles of the ignition switch to build pressure so I decided to check voltage at the relay,at the constant power I have battery voltage along with power coming from ignition and power to relay but have not checked at pumps. Is there supposed to be any restrictor in the return line so not too much fuel goes back into the tank,this thing is driving me nuts and I am tempted to find a carb motor and get rid of the EFI but I dont want it to beat me and would like to figure out what is going on. It acted this way before I put the rear pump in and still is the same and it only had one tank.

[junkyardjeff]

I removed the reservour and blew air through it and seems to be working but tried to find something to bypass it and will try with another filter to see if thats the problem tomorrow.

[rooster]

Dont throw away your old filter, saw those ends off and you can make a jumper that will mate with those hose fittings. The presure in the tank pumps are low the frame pump increases psi alot! Its unlikely the the line between the filter and the fuel rail is blocked, its protected by 2 filters!


Those canisters are a problem child theres alot on the ford truck sites about them.

http://www.supermotors.net/registry/2742/66025