1984 Ford 3.8 TBI fuel pressure

[junkyardjeff]

Still working on the 84 small LTD,last fall the catalytic converters plugged so it sat until recently when I decided to start working on it again so I got the converters gutted so it would run long enough to see what is going on. Drove it to work and started acting like it was out of fuel on the way home and limped it in the driveway and both the pump in the tank and the one on the frame were working,I hooked up my pressure gauge and it was 45 while running which seems high so I need to know the fuel pressure specs and if the regulator is bad and even with too high of pressure could the regulator actually cause a restriction to cause lack of fuel. I did put some stuff in the tank in case there is water in the fuel.

[kb426]

Is the regulator vacuum sensed? If it has a vacuum port, at idle it should be considerably lower than off idle. I don't have specs for one that old. I think that is an eec iii system. I'm reasonably sure that it is a 40lb system. My thought is that high pressure would result in richness. If the regulator froze in the closed position, you could see 80lbs of pressure. If this is a non-vacuum regulator with spring tension only, I think you would have the same situation, however, I'm not sure.

[wayne petty]

last time i checked. the Key on, engine off fuel pressure was 38/39 PSI..

it will change with manifold vacuum..  as the manifold vacuum drops the fuel pressure increases so 44 might not be out of line with the engine running..


FYI..  

3.8 CFI injectors have a green top flow 38 pounds per hour.

5.0 CFI injectors have a dark blue top and flow 59 Pounds per hour.

HO 5.0 CFI injectors have a Grey top and flow 62 Pounds per hour.

the 84 system should be EECIV...  and will have an eec IV connector..    here is info on the EECIV system codes  its far easier unless you have a real scan tool to invest the 35 bucks in the innova 3145 EECIV code reader.

http://www.tomco-inc.com/Tech_Tips/ttt6.pdf

if you need more help.. i have a bunch of stuff on EECIII systems.. these use a rectangular diagnostic connector..  but one can apply vacuum to the Map sensor and feel the TAB and TAD solenoids click out codes. its been so long since i had to do that.  i miss my 83 Tbird 5.0 CFI with a 98 explorer 5.0 roller cam long block and all the turbo coupe suspension upgrades including 16" or 17" wheels.. i forgot.. man would it go around corners..

the EECIII electronics were a little different.. they used 8 Volt relay controls..  put an EECIV relay in and nothing happens.

i have a bunch of 84 EECIV info.. i have MCU info also.. its all kinda scattered in boxes right now.  but its only an hour or so of searching. if you need something.

if the cats were clogged..  you need to verify the thermactor system works perfectly... and the EGR system..

the Diverter valve dumps smog pump air into the upstream exhaust before the oxygen sensors in the manifolds.. this causes the system to go rich and dump excess fuel in trying to burn off the excess air in the exhaust..  this will melt down your cats.. again and again..  it will also kill your fuel economy..  you must also check the pressure output of the smog pump. if it does not create enough pressure the system won't blow when required and will fail the self test performed every start up and then slag the converters  as default is rich.. rich..  rich..

EECIV systems need to be tested after repairs.. KOEO and KOER to get a code like his.. PASS 11, Separator 10, PASS 11..  you will get the best fuel economy and power like that.

if you have an external lamination coil.. square thing.. please check for signs of high voltage leaks..

[junkyardjeff]

It does not seem excessively rich but there is something wrong that plugged the converters.

[wayne petty]

It does not seem excessively rich but there is something wrong that plugged the converters.

see my edit..  thermactor system failure..

[junkyardjeff]

Pump was very noisy and removed ,I doubt the rest of the system was working like it should before the pump was removed. Right now I have to find out why sometimes it acts like it running out of gas if its not water in the gas.

[wayne petty]

Pump was very noisy and removed ,I doubt the rest of the system was working like it should before the pump was removed. Right now I have to find out why sometimes it acts like it running out of gas if its not water in the gas.

that may have an internal low pressure pump feeding the external high pressure pump or a single high pressure pump inside the tank. in looking at the fuel pumps for the 84 LTD 3.8 CFI.. there is an Intank low pressure pump that feeds the external high pressure pump.  testing is easy... disconnect one of the wires to the high pressure pump.. disconnect the inlet hose to the high pressure pump.. turn the key on.. does the fuel start coming out the disconnected fuel hose ..    

fuel filter... is it clogged... if you drop the tank.. don't forget to get the new pickup screen filter..  and toss a super magnet into the corner of the fuel tank away from the sending unit... warning.. cars with analog gauge and cars with digital gauges use DIFFERENT sending units.

voltage drop test.. http://imgur.com/a/wHJue,  please take the whole 3 minute to perform it step by step.  post results if beyond what i wrote down.

voltage drop tests to the fuel pump relay..  voltage drop across the inertia switch..  voltage drop from the positive battery to the inertia switch with the engine running..

do you have a wiring diagram.. for the EECIV V6 system..  if not i can pm it to you.

find the grounds for the ECM.. its going to be close to the ecm... usually 2 black wires to a crimped on ring terminal bolted to the body

when you get the fuel pumps figured out.. run the KOEO and KOER tests.   don't forget about rock auto for the high pressure version.. might get a deal there.

[junkyardjeff]

I think it has two pumps,I barely got it in the driveway and left it running and could feel the tank and felt it vibrating and felt the pump on the frame and both were working. I shut it off and hooked up my gauge and it was 45 running,going to hook up my scanner and run those test after work and i do not have a wiring diagram. It could be water in the tank and treating that too.

[wayne petty]

I think it has two pumps,I barely got it in the driveway and left it running and could feel the tank and felt it vibrating and felt the pump on the frame and both were working. I shut it off and hooked up my gauge and it was 45 running,going to hook up my scanner and run those test after work and i do not have a wiring diagram. It could be water in the tank and treating that too.

wiring diagram for the 84 CFI.  http://imgur.com/a/m2VOe

with some instructions.. pasted in..


if you can get the engine running...

you need to Voltage drop test  the Orange/Black wire into the EEC power Relay.. less than 0.04 volts would be great.. this is Orange/black wire to the positive battery post with a volt meter set at 20 volts DC..

you need to voltage drop test the Black/Green wire with a volt meter to the Negative battery post.. to the engine , and to the BODY, this should also be less than 0.04 volts DC with the meter at 20 volts DC setting.  you may need to change to 2 Volt DC if you get 0.00..


you need to voltage drop test the Yellow wire into the Fuel pump relay to the positive battery post.  less than 0.04 volts would be great.


WHY..  lets look at the Black/orange wire and the Yellow wire.. both of those are individually fusable link circuits from the starter relay B+ post.  corrosion on those ring terminals or freyed wires there is an issue..

lets look at the Black/green stripe wire into the EEC power relay.. that is connected to Pin 60 and the ground wires that bolt to the body near the ECM. this is an easy way to test to see if the computer is properly connected to the NEGATIVE Side.. aka Grounded..   electrons flow from negative to positive.. no ground connection.. no electrons or not enough electrons to do the job at full voltage..

please perform the full six steps of the voltage drop test before doing any others... http://imgur.com/a/wHJue

counting the wires on the starter relay B+ terminal.. taking it apart and wire brushing both sides of the ring terminals.. the threads on the stud.. the bottom side of the nut.. counting wires and reinstalling..

finding where the computer is grounded..  there will be 2 black wires coming out of the harness..  usually up on the firewall.. sometimes down near the ECM..  if its on the firewall.. there should also be a braided ground strap to the back of the motor with them. . and all three tight against the body with the fastener..

[junkyardjeff]

After putting two bottles of dry gas in I drove it about a half hour tonight and seemed fine,done those tests on the scanner and it came up the EGR was inop which I knew and the thermactor system was inop which I knew but it but there was also a code for running rich which got me thinking about the fuel pressure again. I will do all those voltage tests tomorrow.

[wayne petty]

if the Thermactor is not working.. you MUST be sure that its NOT leaking any air into the exhaust...

[junkyardjeff]

When I had the Y pipe off I plugged the tube hole but still could be open at where the pump hooked to it at the motor.

[wayne petty]

the pump can be open.. as long as there is no way for road splash to get back into the pump opening.. many fords use a remote air inlet for these when low mounted..

[junkyardjeff]

I will get to the voltage tests soon but found a TPS sensor wire bare and rubbing a metal bracket so it got taped up.

[junkyardjeff]

Fuel pressure is supposed to be 39 so its a little higher and will look into a regulator,it has a bunch of codes including one for a TPS so it might be cheaper to convert to a carb which we have the parts.