All of a sudden, it's has a hard starting issue.

bossbob · Apr 20, 2017

I just bought this truck for my son, put a new clutch in it and finally got it going. Been driving it for about 200 miles now, it has been flawless until yesterday. Now, out of now where it has a hard starting issue where it will crank for awhile and maybe start and maybe not. Try it again, and it will finally start.

However, after driving around, I can shut it off and it will start right up with no issues.

Where do I start, fuel pump, filter, also, the gas gauge isn't working, could there be some debris clogging the fuel lines?

RonD · Apr 21, 2017

Nice looking older Ranger :icon_thumby:

I would do a 50/50 test just to see if it is spark or fuel that is causing the No Start
When there is a No start stop cranking, pop hood and remove big Air Plenum tube on the intake
Open throttle and spray some gasoline or Quick start(ether) into the intake
Try to start again
If it starts right up then spark is OK, so lack of fuel is the issue
If it doesn't start right up then spark is the issue
50/50

Fuel issue could be loss of fuel pressure when engine is off.
Fuel pressure at the injectors should be 30-40psi, 1997 and earlier Rangers
Pressure is held for MONTHS when engine is off
Outside of a fuel line leak, which you would smell, the Fuel Pressure Regulator(FPR) and the Check Valve inside the fuel pump are what hold the pressure in the system.
Either could leak and you wouldn't smell anything and have no pressure so No Start.

Ford computer will run the fuel pump for 2 seconds when you turn on the key, but only for 2 seconds, so if there was 0 fuel pressure it wouldn't be enough to start engine.
But you can turn key on and then OFF a few times, getting 6 or 8 seconds of fuel pump run time to build up lost pressure.
If engine starts after rebuilding pressure then thats the cause of the no start, lost pressure, and also why it starts easily after being off only a few minutes, its a slow leak of pressure.

You can test if FPR is leaking by remove its Fuel Return line, to see if gasoline is coming out with 1 key turn on

bossbob · Apr 22, 2017

RonD said:
If engine starts after rebuilding pressure then thats the cause of the no start, lost pressure, and also why it starts easily after being off only a few minutes, its a slow leak of pressure.

You can test if FPR is leaking by remove its Fuel Return line, to see if gasoline is coming out with 1 key turn on

Seems like this is exactly whats happening.
So I remove the fuel return line, turn the key to ON and see if fuel come out. If gas is coming out, is it good or bad or if no gas is coming out is it good or bad.

Thanks again.

RonD · Apr 22, 2017

FPR is there to hold fuel pressure in the system, it has a valve and spring inside.
Spring is usually set for about 40psi, so no fuel should come out until pressure gets to 41psi, then FPR valve would open and send fuel back to gas tank, then close again at 39psi
Works like a radiator cap and overflow tank setup

Each time you cycle key on, that 2 seconds of fuel pump run time, increases pressure about 10psi.
So if you turn key on one time and fuel comes out FPR is bad, for sure
No fuel coming out is good but cycle key one more time for 20psi, if it still holds FPR is fine

But no fuel coming out at FPR also means fuel pump is most likely where the leak is, it's check valve is part of the pump not a separate part.
But you can cycle key on and off to build pressure before starting, won't hurt anything, and once engine starts fuel pump is on full time so check valve isn't used.

bossbob · Apr 22, 2017

Is the return line a non pressure line or is it pressurized as well.

Also, where is it located, I was just under the hood and didn't find it.

Tedybear · Apr 23, 2017

bossbob said:
Is the return line a non pressure line or is it pressurized as well.

Also, where is it located, I was just under the hood and didn't find it.

Please DO NOT start pulling fuel lines. If pressure retention isn't the issue, then you'll quickly get covered in gas if done incorrectly

Here's a quick and dirty test that won't burn up the truck or cover you in gas.

Next time it fails to start: Open drivers door and cycle the key. Listen for the fuel pump to prime for those 2 seconds. You can repeat that as well with key cycles. You'll hear an audible "Whine" from the tank.

If you do not hear that? Have someone crank the truck over and slap the bottom of the fuel tank with your hand (like giving it a firm spanking. DO NOT USE A HAMMER!) If the truck suddenly starts to "whine" at the pump, and then starts? Fuel pump is suspect. Spanking the tank while trying to start it will sometimes get the armature to move past any bad spots.

If the pump "whines" okay, then I'd move forward with Ron's tests.

S-

Spott · Apr 23, 2017

Don't pull the fuel line to test the FPR. There are two tests you ought to do instead.

First, get a fuel pressure test gauge and check fuel pressure at the Schrader valve on the fuel rail (looks like a tire valve) after the engine has been sitting for several hours and before you try to start the engine, and then test again after cycling the fuel pump several times, and then a third time after letting the engine sit again for several hours.

You don't actually have to crank the engine to do these tests.

The pressure ought to be 30-40 PSI at all 3 tests. This is the factory approved, professional test method, and is the reason they put that test valve on the fuel rail.

If you've found a low-pressure result to the first and third test, then you can check the FPR. Pull the vacuum line off the back of the FPR, and check for gasoline. If the line is wet with gas, or smells like gas, then you know the diaphragm in the FPR is failing and the FPR needs replaced. Otherwise, suspect the check-valve built into the high-pressure fuel pump.

If you've found a low-pressure result to all three tests, then either one or both of your fuel pumps isn't working, or the fuel filter is clogged, or the FPR is faulty and not allowing pressure to build up high enough. This is an unlikely condition, because you state that the engine runs well once you get it started.

If you get good pressure results from all three tests, then you do not have a fuel-supply problem and need to test other possibilities.

bossbob · Apr 24, 2017

Thanks for all the info, I didn't get a chance to look at it this weekend. But like the idea of a fuel pressure test. I'll try to get to it this week.

bossbob · Apr 26, 2017

I rented a fuel pressure tester and here are my results.

Key on I have 5 psi, cycle the key a few times and it builds up to 10 psi, keep cycling the key on and off and I can get it up to 25 psi. Running at idle it builds to 38 psi, give it a few revs and it remains at 38 psi.

Turn the engine off and it bleeds down to 20 psi with 30 seconds, and down to 10 psi within a minute. After 5 minutes it has 0 psi.

Also, I found this.

I am hoping that this broken vacuum line is the problem. Next question is this part available by itself, or can I use regular vacuum hose as a replacement.

Looks like both ends are different sizes???

Thanks again for any input.

RonD · Apr 26, 2017

No, not the problem.

Fuel Pressure Regulator(FPR) has a vacuum line to keep pressure lower but above 30psi when engine is running, engine off it serves no purpose.
But if the vacuum line on the FPR has fuel inside it then it would mean FPR diaphragm is leaking, and needs to be replaced.

Fuel injection system pressure should remain above 20psi for MONTHS.
So either the FPR is leaking fuel back to tank via the Return Fuel hose
Or the Check Valve inside fuel pump is bad.

You can CAREFULLY pinch return fuel hose with pliers, then cycle key on and off several times to build up pressure again and then watch if it still drops to 0psi
If it holds then replace FPR
If it still drops replace fuel pump

At idle with no vacuum line on FPR 38-42psi would be correct, with vacuum connected the idle psi would probably be closer to 32psi, then when you REVed the engine(vacuum pressure drops) fuel pressure would go up to 38psi in you case

bossbob · Apr 26, 2017

I went out to tape up the broken vacuum line to see if that would help, when I pulled off the end that connects to the FPR it was wet. So, I guess I'll start with a new FPR and replace the vacuum line with whatever I can to make it work.

Thanks again.

RonD · Apr 26, 2017

It is a Vacuum line so it won't separate on its own, you just need a short rubber line of correct inside diameter to slide over the broken section.
It will hold itself in place

Yes if there was gasoline in the vacuum line then replace FPR, that's your pressure loss

bossbob · Apr 27, 2017

I replaced the FPR and the vacuum line, it is still not holding fuel pressure, and hard to start. Also, it is running kind of crappy, rpms are surging at idle, and seems to be starved for fuel under load.

Does the fuel system have to purge any air, what's next?

It ran much better with the old FPR in it. What are the chances I got a bad one out of the box. Got it at autozone, but it's a Sorenson which I believe should be a quality part.

RonD · Apr 27, 2017

Air in fuel system comes out at injectors fairly fast after start up

Cold engine
Remove the Fuel Return line from the FPR

Put a towel down under open FPR port

Turn key on one time

Fuel should not come out of FPR

The spring inside FPR that holds the valve closed should hold fuel pressure up to 40-45psi
When engine is running the vacuum line pulls valve open to maintain 35psi as average fuel pressure, regardless of RPM and fuel demand.

If pressure was 0psi one turn on of the key would get about 10-15psi, two turns on and off about 20-25psi

If FPR is good and fuel injectors are not leaking(engine blowing black smoke and MPG is in the toilet) then all that is left is the Check valve inside the fuel pump.
So that's where you will be going next

Could also be a crack or leak in the lift hose from fuel pump to the top of the tank, but in any case into the tank you should go

bossbob · Apr 27, 2017

Thanks,

I'll pull the return line tomorrow with the key on only, right? Not with the engine running?

I am not blowing any smoke, gas gauge doesn't work but only have about 150 miles on a full tank.

As I mentioned before, I just got this truck and working the bugs out, filled it up with gas as soon as I put the clutch in. It read full for about 10 miles, then 1/2, 1/4, and empty within maybe 20-30 miles. But seemed to be running really good until this fuel problem.

All of a sudden, it's has a hard starting issue.

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