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Hydrolock in cylinder 6


palsdot

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I recently had my 88 STX running poorly, missing and blowing light blue almost white smoke. It stalled at a stop and then started again and I drove a few hundred feet and it started to cut out and belch smoke. Tried to start again and the motor was locked up. I waited a couple of days and tried to start again and it turned over about four times and locked up again. I thought that maybe I had a blown head gasket and had some coolant locking up the motor so I pulled all the plugs. When I pulled number six fluid came out but it was not coolant it was fuel. I am assuming that the injector was stuck open and filling the cylinder with fuel.

I would think that if the pressure regulator was bad that it would have had an issue with more than one cylinder? Should I replace all of the injectors when I pull the fuel rail or just the one that suspect to be the problem?
Can I check the injector while it is out to verify that it is the injector that is bad and not a possible short in the wire?
 


RonD

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Generally yes if the other spark plugs were dry then the wet one or wet cylinder would have the leaky injector.

No real reason to replace them all.

Test OHMs on all though.
11 to 16 OHMs


All injectors get 12volts when key is on, the red wire at each injector
The computer Grounds each injector to open it.
Check that #6 wire isn't shorted to Ground
 

palsdot

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I tested OHMS on all injectors and they all read 15. If they all check out at 15 does that mean that it is not sticking?
I pulled the fuel pump solenoid and turned the key to on position and all injector wires lit up my test light. I have not yet checked to make sure that they are pulsing yet. I need to make sure everything is clear and have someone help me crank it, that is what would tell me if cylinder 6 has a ground short, correct?
 

palsdot

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How do I test the wires to make sure that they are not shorted to ground? I thought I could just crank the engine and see if my test light pulsed but when I did that I didn't see much of a pulse, it seemed like it was more of a dimming of the light but still looked constant.
Thank you!
 

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Test light should not be on, if it is then when that connector was plugged into injector it would open.

Injectors get 12volts with key on, Red wire, but the "other" wire should NOT be a ground.
Computer grounds that wire for only a few milliseconds to open injector, test light might glow while cranking, but you really need a Noid Light to test for Ground pulse from computer.

In your case it does read like the "other" wire is Grounded all the time.
'88 will use Batch Fire Injection.
On a V6 3 injectors will share a Computer Ground wire.
You may have 3 injectors that open with Key On.

There are only two different color "other" wires.
Find an injector using a different color wire for Ground and test it.

This is a diagram of the computers Pin wiring: http://www.auto-diagnostics.info/ford_eec_iv

Pins 58 and 59 are the two Grounding wires that go to the injectors, 3 each.
You may need to pull off this 60-pin connector and then test each for Ground, a shorted wire, if wire is OK then problem is IN the computer
 

palsdot

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So I replaced the injectors and turned the key to engage the fuel pump. I didn't have the vacuum line on the pressure regulator and when the pump kicked on fuel shot out of the vacuum line. That would mean that the regulator is shot, correct?
 

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Yes, and that would explain the flooded engine as well.

That vacuum line often goes to upper intake just above #6.
Flooding when vacuum is high, low RPMs, and fuel pushed into intake from the fuel pressure after shut down, then drains down to #6, and if intake valve is open.............hydro-lock at next start up.
 
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palsdot

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So I replaced the injectors, fuel pressure regulator and changed the oil. Truck is running but when I drive it in fifth gear it acts like it is flooding. If you are at lower RPM and put the pedal to the floor it almost sounds like a 4-barrel opening up but doesn't respond until the RPMs pick up. I bought the injectors off of E-bay, is there a chance that they are not the correct ones and are too big?
 

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2.9l did use a Speed Density fuel injection system, so larger injectors could throw it off.

Stock injectors are 14lbs/hour

Is the SPOUT Connector inserted?
The delay in response and loss of power could be spark timing.
TFI distributor does have centrifugal advance but needs SPOUT advance from computer to get full advance and responsive advance.
 

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The SPOUT connector is in place.
I will need to get the specs from the seller, this is what was listed when I bought them.
"1989-1993 Flow Matched Fuel Injectors Set for Mazda, Ford 3.0 V6 F47E-A2E"
According to the vehicle fit sheet on the site they should have fit.
I unplugged the vacuum line to the pressure regulator to see if it would improve the performance by not asking for as much fuel, it was either my mind playing tricks on me or it did seem to improve.
Another issue that I had last night was that truck died while I was driving down the road like someone shut the key off. I was able to start it back up to have it die again with in a few hundred yards. I need to look at the ground to the fuel pump as it has given me fits in the past but I believe this to be a separate issue.
 

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Yes, those are 14lbs/hr injectors

The fuel pressure regulator(FPR) is set for 35-45psi, that is done with a spring inside it holding the valve closed, if pressure gets above 40psi spring is pushed open and fuel is sent back to gas tank.

The vacuum hose will start pulling open the valve, against spring pressure, when vacuum in intake is above 16", usual vacuum at idle is 18-20", when throttle is opened vacuum drops and FPR spring takes over.

If you have a pressure gauge hooked up and engine idling you should see 30-40psi
If you remove the vacuum hose it should jump up to 35-45psi that's the springs pressure setting, if it doesn't go up then spring is probably wearing out or valve is leaking a bit.
Not a big deal unless it is leaking into the vacuum hose side of FPR.
Running without vacuum hose connected is fine but shouldn't change performance.

Fuel pressure below 20 psi can effect performance, but above that the computer is fine.
Computer adjusts the open time of each injector a few times a second, as per O2 sensor oxygen levels.
If pressure is lower computer opens injector longer to get correct air/fuel mix and burn.
If pressure is higher it shortens injector open time.
So there is a large range of acceptable fuel pressure for engine to operate correctly.

The computers sole purpose is to calculate open time(pulse width) for the fuel injectors.
MAP sensors tells it the engine load, via vacuum level in the intake.
TFI tells it tells it the RPM of the engine, 2.9 LITER engine uses XX amount of air per RPM
O2 sensor tells it if burn was Lean(high oxygen) or Rich(low oxygen)

And it calculates fuel needed based on MAP and RPM then fines tunes that based on O2 feedback.

One of the reasons there is no Fuel Pressure Sensor, which would be easy to add, is that it isn't needed, if pressure gets too low you would get a CEL and Lean code.

If fuel pump is shutting off intermittently then that would be an issue
 
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palsdot

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I will check fuel pressure tonight. The only way to know if a fuel pump is intermittently shutting off would be to be able to watch the pressure while driving it until the symptoms occur, correct?
 

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Yes, pretty much.

I you have a buddy that is an electrician you could see if his amp meter worked on the inertia switch wire, it is in the cab, passenger side footwell.
Amp meter just clamps around the wire, no hook up required.

If motor(fuel pump) shuts off amps would drop.

Electric motor is about 1 ohm resistance so would draw about 12amps at 12volts

Corroded connectors or grounds, cause a voltage drop, even a little corrosion and the 12volts is only 8 volts at the pump.

People tend to think of 12volts as being an "in" and Ground as an "out", doesn't work that way.
Look at the Dash temp gauge, for example, it gets 12volts when key is on.
Sender on the engine is a heat sensitive resistor, and the Ground for the temp gauge.
As the sender heats up resistance goes up, and so does gauge needle.
The 12volts isn't changing, the Ground is.
So loose or corroded ground wire effects the whole circuit.
 
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palsdot

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Fuel pressure is good. I fixed what I thought was the bad ground and it improved but I am still getting an intermittent loss of power or something somewhere because I can be driving and feel a little buck and when I look at the panel a light comes on for a second like the key was turned off and back on. I continued driving and it died like the key was turned off and the lights will come on again. I turned the key offor and back on it it takes off again. Seems more like a short to the ignition or computer now, because of the way it dies is more like electrical cut off and not stumbling like it is running out of fuel.
 

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Well you are narrowing it down :)

For $7 I would replace the EEC Relay, but test its socket.
Test battery voltage, i.e. 12.3, 12.5, 12.7, get exact voltage at battery.

With key off 1 slot in socket should have 12volts(battery voltage), this is from a 30amp fuse
Then turn key on, another slot should now have 12volts, not 9 or 10, full 12, that's the voltage that holds EEC relay closed, if EEC relay pops open engine shuts down
 

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