Ranger Fuel System Problem
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Ranger Fuel System Problem
The truck is my son's '87 Ranger 4x4
The engine is a 2.9 with TBI
The other day it overheated - it turned out to be a dead water pump. My son changed the water pump. At the same time he changed the oil becuse of the thermal stress it must have seen from overheating. Water pump job went fairly smoothly.
He added coolant and went to start it up - no go - it cranked, but no fire.
We sprayed some fuel in the throttle body & it caught - So we have ignition, but fuel isn't getting there.
The problem seems to have something to do with the fuel pump relay - I we bypass that, the in-tank fuel pump runs (but the truck still won't start)
We changed the relay, no help.
If I test the plug for the relay, I find some stuff I think is weird - There is an "always hot" line coming in that has 12V on it. Obviously the line to the pump has 0V. The part that has me very confused are the signal lines to the relay. There is one red line that comes (I assume) from the ignition switch. That shows 12V if the ignition is on, 0V if it is off. So far I'm following this. Then there is a tan line that goes to the EEC (computer). That also show 12V with the ignition on and 0V with the ignition off.
If I understand how a realy works, there needs to be a difference in voltage to activate the switch - 12V on both sides is the same as 0V on both sides to the circuit - no difference in potential, no response - Or do I have that wrong?
We also realized that this truck also has a rail-mounted high-pressure fuel pump. I haven't torn that out yet to see if it works when I give it 12V - that's my next stop.
This is making me crazy, and my son and I having to shuttle each other back & forth to work is getting old - Anyone have any ideas?
We'll change out whatever we have to - I just don't want to just start changing things at random until we've replaced the entire fuel system.
The engine is a 2.9 with TBI
The other day it overheated - it turned out to be a dead water pump. My son changed the water pump. At the same time he changed the oil becuse of the thermal stress it must have seen from overheating. Water pump job went fairly smoothly.
He added coolant and went to start it up - no go - it cranked, but no fire.
We sprayed some fuel in the throttle body & it caught - So we have ignition, but fuel isn't getting there.
The problem seems to have something to do with the fuel pump relay - I we bypass that, the in-tank fuel pump runs (but the truck still won't start)
We changed the relay, no help.
If I test the plug for the relay, I find some stuff I think is weird - There is an "always hot" line coming in that has 12V on it. Obviously the line to the pump has 0V. The part that has me very confused are the signal lines to the relay. There is one red line that comes (I assume) from the ignition switch. That shows 12V if the ignition is on, 0V if it is off. So far I'm following this. Then there is a tan line that goes to the EEC (computer). That also show 12V with the ignition on and 0V with the ignition off.
If I understand how a realy works, there needs to be a difference in voltage to activate the switch - 12V on both sides is the same as 0V on both sides to the circuit - no difference in potential, no response - Or do I have that wrong?
We also realized that this truck also has a rail-mounted high-pressure fuel pump. I haven't torn that out yet to see if it works when I give it 12V - that's my next stop.
This is making me crazy, and my son and I having to shuttle each other back & forth to work is getting old - Anyone have any ideas?
We'll change out whatever we have to - I just don't want to just start changing things at random until we've replaced the entire fuel system.
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Oh yeah - ignore the paragraph about the rail-mounted pump - it works, and the fuel filter isn't clogged - I can pump fuel up to the fuel pressure regulator.
Originally Posted by LBDumont
The truck is my son's '87 Ranger 4x4
The engine is a 2.9 with TBI
The other day it overheated - it turned out to be a dead water pump. My son changed the water pump. At the same time he changed the oil becuse of the thermal stress it must have seen from overheating. Water pump job went fairly smoothly.
He added coolant and went to start it up - no go - it cranked, but no fire.
We sprayed some fuel in the throttle body & it caught - So we have ignition, but fuel isn't getting there.
The problem seems to have something to do with the fuel pump relay - I we bypass that, the in-tank fuel pump runs (but the truck still won't start)
We changed the relay, no help.
If I test the plug for the relay, I find some stuff I think is weird - There is an "always hot" line coming in that has 12V on it. Obviously the line to the pump has 0V. The part that has me very confused are the signal lines to the relay. There is one red line that comes (I assume) from the ignition switch. That shows 12V if the ignition is on, 0V if it is off. So far I'm following this. Then there is a tan line that goes to the EEC (computer). That also show 12V with the ignition on and 0V with the ignition off.
If I understand how a relay works, there needs to be a difference in voltage to activate the switch - 12V on both sides is the same as 0V on both sides to the circuit - no difference in potential, no response - Or do I have that wrong?
We also realized that this truck also has a rail-mounted high-pressure fuel pump. I haven't torn that out yet to see if it works when I give it 12V - that's my next stop.
This is making me crazy, and my son and I having to shuttle each other back & forth to work is getting old - Anyone have any ideas?
We'll change out whatever we have to - I just don't want to just start changing things at random until we've replaced the entire fuel system.
The engine is a 2.9 with TBI
The other day it overheated - it turned out to be a dead water pump. My son changed the water pump. At the same time he changed the oil becuse of the thermal stress it must have seen from overheating. Water pump job went fairly smoothly.
He added coolant and went to start it up - no go - it cranked, but no fire.
We sprayed some fuel in the throttle body & it caught - So we have ignition, but fuel isn't getting there.
The problem seems to have something to do with the fuel pump relay - I we bypass that, the in-tank fuel pump runs (but the truck still won't start)
We changed the relay, no help.
If I test the plug for the relay, I find some stuff I think is weird - There is an "always hot" line coming in that has 12V on it. Obviously the line to the pump has 0V. The part that has me very confused are the signal lines to the relay. There is one red line that comes (I assume) from the ignition switch. That shows 12V if the ignition is on, 0V if it is off. So far I'm following this. Then there is a tan line that goes to the EEC (computer). That also show 12V with the ignition on and 0V with the ignition off.
If I understand how a relay works, there needs to be a difference in voltage to activate the switch - 12V on both sides is the same as 0V on both sides to the circuit - no difference in potential, no response - Or do I have that wrong?
We also realized that this truck also has a rail-mounted high-pressure fuel pump. I haven't torn that out yet to see if it works when I give it 12V - that's my next stop.
This is making me crazy, and my son and I having to shuttle each other back & forth to work is getting old - Anyone have any ideas?
We'll change out whatever we have to - I just don't want to just start changing things at random until we've replaced the entire fuel system.
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Joined: Dec 2001
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Welcome to the forum 
Are the injectors firing when it cranks? Have the igniton module checked. Recheck all of the plugs on the engine as well to make sure none were bumped during the pump change.
Are the injectors firing when it cranks? Have the igniton module checked. Recheck all of the plugs on the engine as well to make sure none were bumped during the pump change.
