Hard starting when hot

[cp2295]

If i start my truck up approx 20 minutes to 2 hours after i turn it off, it takes a while to crank it over. in the morning it starts right up. If i let it sit for about 5 minutes it starts right up as well. I know the trick of turning the key to the on position a few times, and that always works, so i figure it must be fuel related.

I tried changing the fuel filter today but the end of the hose facing the tank on the filter would not come off, so im taking it to the shop and having them do it.

My long term fuel trims are at about 15% on the lean side if that has any correlation.

I tried hooking up a fuel pressure gauge and it just kept spraying fuel out everytime i would screw it down (it was the rental one from O'Reilly's). Probably gonna try using a different gauge and see if there's a leak.

How long should the fuel pressure hold? It's a 99 ranger so it should be at 65 PSI right? It has no return line.

For some more background:
Where the fuel line connects near the driver's side fender, that braided line on my truck was tearing, so i was worried about it. I didn't really feel like changing the whole line out, so i took off that braided line via pipe cutters, and cut the steel nice and clean. I then got another one of those braided lines from the JY and cut it nice and clean as well. then i took some fuel injection hose, a couple of fuel hose clamps, and connected the two steel ends. I don't smell any gas or anything, but i was wondering if maybe that is restricting flow or leaking so small i can't tell?

The truck runs just fine when driving, has plenty of power, no chugging up hills or anything.

 

[RonD]

Yes, 65psi on the returnless fuel system.

Fuel pump on your model has a check valve(back flow preventer), so pressure should stay above 50psi for days.

Leaky injectors or leaky fuel lines will cause slow steady pressure drop, quick drop would be the check valve.

 

[cp2295]

Okay is the check valve separable from the pump?

 

[RonD]

It might be, when I have looked at pictures of the pump assemble there is a part on the hose that looks very much like a check valve.

 

[Tbarnes93]

its the engine coolant temp sensor my truck used to do the same thing. your engine is reading below the actual temp therefore no start until cold.

 

[cp2295]

I don't think it's that, the temp always goes up from a reasonable temperature when cold and then raises to 190 then stays there. Seems to be working fine but I'll change it out and see what happens

 

[RonD]

I believe he means the ECT sensor that is only used by the computer to detect engine temp. It is a 2 wire sensor on the intake or t-stat housing.

The dash board temp gauge uses a 1 wire sender, it wouldn't effect starting.

The ECT sensor causes computer to run engine rich when cold and then normal fuel mix once warmed up.
If it was reading cold then warm engine would have a harder time starting with rich mix.

 

[cp2295]

Should I go motorcraft on this one? I heard people had issues with aftermarket ect sensors

 

[RonD]

I would just test ECT sensor with OHM meter and some hot water, the ECT is a simple resistance sensor not much to go wrong, it can fail, just like a temp sender(dash board gauge) it's just not likely to fail.

OHM readings seen here
http://0.tqn.com/d/autorepair/1/0/I/A/41928895.gif

 

[cp2295]

Okay so just boil the water and then set my voltmeter to the ohms setting and touch the two prongs on the posts and see what it reads? I've never done an ohms test before

 

[RonD]

yes, thats all

OHM meter has a battery inside, it test resistance in the electrical flow between two points, there is no +/-

K ohms is 1,000 ohms

so if spec for 212degF(boiling water) is 2.07 K ohms then you would set meter for K or if automatic meter it should show 2.07k

This is a resistance sensor so ohms are not written in stone, appox. is the rule of thumb
Ohms should go up as sensor cools and ohms should go down as it heats up, and be approx. 2.00k when water boils

 

[cp2295]

Gonna have to bump this. It's getting harder to start and turning to the on position doesn't help. I did it 7 times and it still started up the same, cranked over for forever then finally springs to life. Still starts up perfect in the cold and 0-5 minutes after I turn it off. Anybody got any ideas there? Still haven't been able to hook up a fuel pressure gauge the ones for rental just leak and I can't afford one

 

[onelif2live85]

Did you ever test the ECT I did not see that you ruled that out?

Sent from my LG-MS870 using Tapatalk

 

[RonD]

I would get a can of starting fluid(ether), next time there is a no start, pull off PCV hose or Power brake hose from intake, spray some starting fluid into intake, replace hose.
Crank engine
If it fires then fuel or lack of it is the issue
If it doesn't fire then spark is the issue

There are 3 coils in the coil pack so not sure heat would effect all 3, one of them yes but all 3 would be odd.

Check the wires coming from the CKP(crank position) sensor, CKP pulse is fairly weak normally(1volt), so a hot wire might raise resistance enough to prevent computer from seeing the pulse, although I would expect to see a CEL if that was the case.

As said heat increases resistance in wiring, so guessing there is a corroded connection somewhere that is heating up with engine would be best guess.
With engine cold I would measure coil voltage and injector voltage with key on/engine off, then do the same after warming up engine, see if either is dropping in voltage

 

[shane96ranger]

Have you checked to see if the fuel pressure regulator is leaking fuel into the vacuum line after you shut it off?