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1999 trooper 3.5 long crank start

PostPosted: Fri Oct 16, 2020 4:18 pm
by riggler
Hi, my 1999 3.5 trooper has lately seem to be taking 5 to 15 seconds to fire when warmed up, something I havent noticed before. On cold starts it usually starts in less than 5 seconds.

1999 3.5 trooper bought new 12/1999
208,000 miles, about 110k on engine rebuild
newer battery, alternator making 14.2 volts
starter is about 2 months old. along with the plugs
fuel filter 1 year old
the fpr and the injectors are original, and im thinking that is where is should be looking
What say you guys?
Thanks in advance, steve

Re: 1999 trooper 3.5 long crank start

PostPosted: Sat Oct 17, 2020 6:25 pm
by Buster28
Connect a Fuel Pressure gauge to the fuel rail test port and turn the Ignition Switch to Run for 15 seconds and back to Off without Cranking the engine. The expected pressure is about 40 psi and it should remain close to this value for several minutes. If the pressure drops to zero quickly there is an internal or external leak which is likely the cause for the delay in getting the engine to start.

Re: 1999 trooper 3.5 long crank start

PostPosted: Sat Oct 17, 2020 7:17 pm
by riggler
Buster28 wrote:Connect a Fuel Pressure gauge to the fuel rail test port and turn the Ignition Switch to Run for 15 seconds and back to Off without Cranking the engine. The expected pressure is about 40 psi and it should remain close to this value for several minutes. If the pressure drops to zero quickly there is an internal or external leak which is likely the cause for the delay in getting the engine to start.


Thank you for your reply Buster...
so if i see a pressure drop the likely cause is the fuel pressure regulator ?

Re: 1999 trooper 3.5 long crank start

PostPosted: Sun Oct 18, 2020 3:44 am
by Oro
No, it can be any part in the system. The first thing to change would be a fuel filter, cheap and they do clog and cause a pressure drop. They can easily be good for 100k miles but has it ever been changed in 208k on the chassis?

Just an example but why its not automatically an FPR.

Also, if situations are worse warm than cold, that argues for an electrical part, where gaps expand. like a CPS, etc. Some hall sender that is failing.

Can be many reasons, have to go carefully through it. I have never been able to get a car starting reliably cold/warm using this diagnostic tree:

https://www.ifitjams.com/starting.htm

Run down the right side to see most common warm start issues. Filter, F pump, vacuum. Not all, but a powerful tool and lead.

Re: 1999 trooper 3.5 long crank start

PostPosted: Sun Oct 18, 2020 5:53 am
by Buster28
riggler wrote:
Buster28 wrote:Connect a Fuel Pressure gauge to the fuel rail test port and turn the Ignition Switch to Run for 15 seconds and back to Off without Cranking the engine. The expected pressure is about 40 psi and it should remain close to this value for several minutes. If the pressure drops to zero quickly there is an internal or external leak which is likely the cause for the delay in getting the engine to start.


Thank you for your reply Buster...
so if i see a pressure drop the likely cause is the fuel pressure regulator ?

Normally, when the Ignition Switch is placed in Run as part of the startup sequence the the Fuel Pump starts and pressurizes the fuel rail and injectors to about 40 psi. When the engine is Cranked injector pulses and spark plug signals are generated. If there is no fuel in the rail it takes longer to start. The problem could be regulator, but run the pressure test first to check the pressure.

Also, the Camshaft Position (CMP) sensor is used to determine the first cylinder to fire on start up, if the CMP is inoperative it take longer to start the engine. However, CMP sensor problem usually sets a DTC and illuminates the CEL.

Re: 1999 trooper 3.5 long crank start

PostPosted: Sun Oct 18, 2020 11:19 am
by riggler
[quote="Oro"]No, it can be any part in the system. The first thing to change would be a fuel filter, cheap and they do clog and cause a pressure drop. They can easily be good for 100k miles but has it ever been changed in 208k on the chassis?

thanks for the replys guys
ordered a pressure gauge kit and filter
filter is at most 2 years old, but they are cheap enough that it makes sense to replace just to rule it out (after pressure test of course)

Re: 1999 trooper 3.5 long crank start

PostPosted: Mon Oct 19, 2020 11:29 pm
by riggler
Buster28 wrote:
riggler wrote:
Buster28 wrote:Connect a Fuel Pressure gauge to the fuel rail test port and turn the Ignition Switch to Run for 15 seconds and back to Off without Cranking the engine. The expected pressure is about 40 psi and it should remain close to this value for several minutes. If the pressure drops to zero quickly there is an internal or external leak which is likely the cause for the delay in getting the engine to start.


Thank you for your reply Buster...
so if i see a pressure drop the likely cause is the fuel pressure regulator ?

Normally, when the Ignition Switch is placed in Run as part of the startup sequence the the Fuel Pump starts and pressurizes the fuel rail and injectors to about 40 psi. When the engine is Cranked injector pulses and spark plug signals are generated. If there is no fuel in the rail it takes longer to start. The problem could be regulator, but run the pressure test first to check the pressure.

Also, the Camshaft Position (CMP) sensor is used to determine the first cylinder to fire on start up, if the CMP is inoperative it take longer to start the engine. However, CMP sensor problem usually sets a DTC and illuminates the CEL.

Thanks buster !
I ordered a fuel pressure gauge kit, but Im wondering if it comes with the right fitting, by chance do you remember what the 3.5 fuel pressure port size is ?

Re: 1999 trooper 3.5 long crank start

PostPosted: Tue Oct 20, 2020 4:05 am
by Buster28
I am reasonably sure the fitting on the Fuel Pressure gauge and fuel rail s standard, I have used mine on my Isuzu V6 and several GM and import vehicles with no problem.

Re: 1999 trooper 3.5 long crank start

PostPosted: Tue Oct 20, 2020 10:34 pm
by riggler
Buster28 wrote:I am reasonably sure the fitting on the Fuel Pressure gauge and fuel rail s standard, I have used mine on my Isuzu V6 and several GM and import vehicles with no problem.

You were right, my amazon fuel pressure gauge kit had the correct fitting...

So with key on , not starting, I saw no pressure on the gauge, Start the engine, saw an indicated 36 psi, shut it off , it immediately went to zero on pressure gauge

I then changed the fuel pressure regulator, that snap ring is a real challenge on the install side (yes i did get the screen and o rings out also)
the bowl had a small bit of sediment in the screen, a lot less than i figured since this was the one it came with when i bought it...

turn key on to just before the start, no indicated pressure on gauge, start the engine , gauge went to 40 psi, then settled in at 38/39 psi, shut the engine off, and again the gauge immediately goes to zero.

The warm starting crank time was vastly improved, and seat of the pants driving I thought it pulled a big hill betterthan it has been recently. I should have a fuel filter tomorrow and will install that next.

Can what i observed be correct, i mean no key on pressure till it starts ? Or Is it possible that my new amazon fuel pressure gauge from china has a leak somewhere that i cant see or smell causing me to see what i see?
Im supposed to take a 4 day trip starting thursday, and Im now wondering if it is a good idea......

Thanks for listening, steve

Re: 1999 trooper 3.5 long crank start

PostPosted: Wed Oct 21, 2020 5:22 am
by Buster28
riggler wrote:turn key on to just before the start, no indicated pressure on gauge, start the engine , gauge went to 40 psi, then settled in at 38/39 psi, shut the engine off, and again the gauge immediately goes to zero.

You could have one or more leaky fuel injectors or a leak in the hose inside the tank or the fuel pump check valve leaks.
If you install a check valve in the fuel hose you can determine if the problem is on the injector side or the tank side of the check valve. Just installing a check valve may be the best long term solution. A fuel line one way check valve is about 9 bucks on Amazon.

Re: 1999 trooper 3.5 long crank start

PostPosted: Wed Oct 21, 2020 8:53 pm
by riggler
Buster28 wrote:
riggler wrote:turn key on to just before the start, no indicated pressure on gauge, start the engine , gauge went to 40 psi, then settled in at 38/39 psi, shut the engine off, and again the gauge immediately goes to zero.

You could have one or more leaky fuel injectors or a leak in the hose inside the tank or the fuel pump check valve leaks.
If you install a check valve in the fuel hose you can determine if the problem is on the injector side or the tank side of the check valve. Just installing a check valve may be the best long term solution. A fuel line one way check valve is about 9 bucks on Amazon.


Looking for real estate near the fpr for a check valve installation is looking like a challenge to me, would it be just as effective if i put it in line directly after the fuel filter down on the frame ?
thanks.

Re: 1999 trooper 3.5 long crank start

PostPosted: Thu Oct 22, 2020 7:07 am
by Buster28
riggler wrote:Looking for real estate near the fpr for a check valve installation is looking like a challenge to me, would it be just as effective if i put it in line directly after the fuel filter down on the frame ?
thanks.

Install it by the fuel filter, get the correct size to match the hose ID.

Re: 1999 trooper 3.5 long crank start

PostPosted: Wed Nov 11, 2020 9:13 am
by riggler
So with the addition of the check valve after the fuel filter hot restarts are pretty much back to normal, thank you for your input !
My next question is do I start shopping for a new in tank fuel pump or is it possible that I can get another couple of years out of it with the check valve ?

Re: 1999 trooper 3.5 long crank start

PostPosted: Wed Nov 11, 2020 2:51 pm
by Buster28
I would not do anything except drive it, the external check valve is good enough.