Head gasket leak?? Bad luck?? Help.

95bajaguy · Aug 22, 2016

I am still fighting the same battle with my truck that i have for the last few months. It has a issue with starting after sitting for a while. Its sounds like only a few cylinders are running and spits and sputters and the occasional backfire for about 10 seconds until it goes into normal idle. Also note that replacing spark plugs fixes this problem for about a day or 2 then its back to how it was. At first i thought it was leaking injectors filling the cylinders (because i lose fuel pressure when truck is off). I replaced all 6 injectors and spark plugs at the same time and it was running fine for probably 2 weeks or so, then it started having the starting problems again. (I also still lose fuel pressure, but alittle slower now) Now it even does it with a warm start. (After sitting for 30 mins or so). I AM LOST. What i want to know is, has anyone had this problem and could it be fluid getting in the cylinders. Possible head gasket leak? I do lose coolant. Also why are my plugs being fouled almost immediatly? If anyone knows anything that could help i would appreicate it.

Thanks.

rusty ol ranger · Aug 23, 2016

Could be the check ball on the fuel pressure regulator. Id try changing the regulator. A head gasket would cause coolant/compression loss, not fuel pressure.

95bajaguy · Aug 23, 2016

rusty ol ranger said:
Could be the check ball on the fuel pressure regulator. Id try changing the regulator. A head gasket would cause coolant/compression loss, not fuel pressure.

Im not saying the fuel pressure loss is because of a head gasket,

They are 2 seperate issues. The fpr does not have any problems.

RonD · Aug 29, 2016

When a spark plug "fouls" what does the tip look like?
Black, carbon fouling
Oily black, leaking valve guide seals
White steam cleaned, coolant leaking into that cylinder, a head gasket or cracked head issue

In 1995 Ranger/Mazda fuel pressure needs to be 30-40psi at the injectors, system will hold pressure for MONTHS not hours, days or weeks, MONTHS
Two valves hold this pressure
Fuel Pressure Regulator's pressure valve
Fuel pumps internal Check Valve, back flow preventor

Easy way to see if injector might be leaking is to shut off the engine, wait 15min then pull off the air intake from the upper intake manifold, open throttle and smell for gas smell, if injector is leaking you WILL smell gas.
With fuel injection, the injectors are shut off with the key being turned off, but engine RPMs are still above 600 at that time, so any gas smell will be pulled out of the intake as engine RPMs drop to 0.
Leaking injector is the only way gas smell could return

There are ways to check which pressure holding valve might be leaking.
Use visegrips.
After shutting off engine, CAREFULLY pinch the IN fuel line in the engine bay, don't crush it just pinch it closed
wait 15 minutes and see if pressure is still above 25psi
If so remove visegrips and wait 15min again, test pressure, if it has dropped then Fuel Pump check valve is leaking.

You can do the same test for the Return fuel line on the Fuel pressure regulator.

If fuel pressure is under 15psi when starting, engine will struggle and misfire until pressure can build up again.
You can cycle the key on and off 3 times before trying to start engine, that will cause fuel pump to run 3 times, and should build pressure up to above 25psi for starting.
Each time key is turned on fuel system gets about 10psi of pressure

95bajaguy · Aug 29, 2016

RonD said:
When a spark plug "fouls" what does the tip look like?
Black, carbon fouling
Oily black, leaking valve guide seals
White steam cleaned, coolant leaking into that cylinder, a head gasket or cracked head issue

In 1995 Ranger/Mazda fuel pressure needs to be 30-40psi at the injectors, system will hold pressure for MONTHS not hours, days or weeks, MONTHS
Two valves hold this pressure
Fuel Pressure Regulator's pressure valve
Fuel pumps internal Check Valve, back flow preventor

Easy way to see if injector might be leaking is to shut off the engine, wait 15min then pull off the air intake from the upper intake manifold, open throttle and smell for gas smell, if injector is leaking you WILL smell gas.
With fuel injection, the injectors are shut off with the key being turned off, but engine RPMs are still above 600 at that time, so any gas smell will be pulled out of the intake as engine RPMs drop to 0.
Leaking injector is the only way gas smell could return

There are ways to check which pressure holding valve might be leaking.
Use visegrips.
After shutting off engine, CAREFULLY pinch the IN fuel line in the engine bay, don't crush it just pinch it closed
wait 15 minutes and see if pressure is still above 25psi
If so remove visegrips and wait 15min again, test pressure, if it has dropped then Fuel Pump check valve is leaking.

You can do the same test for the Return fuel line on the Fuel pressure regulator.

If fuel pressure is under 15psi when starting, engine will struggle and misfire until pressure can build up again.
You can cycle the key on and off 3 times before trying to start engine, that will cause fuel pump to run 3 times, and should build pressure up to above 25psi for starting.
Each time key is turned on fuel system gets about 10psi of pressure

Ron. It runs at 35 psi when switch is set to on. When running at idle it runs around 30 psi.

Injectors are new but I guess not everything works right. I'll do some tests that you mentioned and get back to you. I'll get a picture of a plug for you too. Thanks

95bajaguy · Aug 29, 2016

Also Ron, I am loosing coolant but it has always done it. I can't found any external leaks

RonD · Aug 29, 2016

Just Google: Spark plug tip images

Spark plug condition is well documented in images no need to post a picture.

Cold engine
Remove radiator cap
Start engine
While engine is running top up coolant in rad, use water if you want

Watch for the coolant coming back out of rad cap opening after topping it up, it shouldn't.
If coolant keeps being pushed out then you have a head gasket leak or cracked head, the pressure from a cylinder firing is pushing "air" into the heads cooling system, the air displaces the coolant so coolant is pushed out of rad cap opening each time that cylinder fires.

If coolant doesn't come out of rad cap opening then there is no head gasket or cracked head issue.

Check overflow hose for leaks, you can lose coolant from that hose and it won't be noticed as a drip on the ground.

95bajaguy · Aug 29, 2016

Ron, it's norMal for coolant to come out when the engine runs. That's what the overflow box is for. If it comes out like a geyser that's a different story

RonD · Aug 29, 2016

No, it is not normal for coolant to come out of the radiator when engine is cold.
You can get a bit of a surge for 1 or 2 seconds on startup but nothing after that.

Vehicle were used for years without overflow tanks, they just used slightly higher pressure caps and if engine got too hot, and coolant expanded too much, cap would open and coolant would come out thru a hose that went down the side of the rad and dumped it on the ground, lol.

Overflow tank is a better idea because if does self purge air from the system.

Cold engine rad cap off should not belch coolant, if it does then there is a problem.......for sure

Head gasket leak?? Bad luck?? Help.

95bajaguy

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Im a Jeep guy now.

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