Fuel delivery issue?

[thomas.mcniven]

Hi everyone. I'm new to the forum. I've been looking around for a while, and I picked up a FiST this past summer. It now has 96k miles.

I've been having some type of fuel issue since the fall that I need some help with. I noticed my car started stalling shortly after startup, but only after longer drives. For example, if I drive 40 miles to work, then leave again after 10 minutes, the car will stall withing the first 500 yards. It will start right back up. Sometimes it stalls twice and starts right back up each time, but after that it works fine again. It only does it after a warm start. At first I thought it might be the "stalling after gas up issue" but then realized it's not just after getting gas. It does it no matter what the fuel level is. I always use "top tier" gas at 91 octane, which is the highest we have in Utah due to the altitude. At first I used to top off, but then read that I shouldn't. I've replaced the parts that would have been affected since then. The car has an accessport v3 with mountune tune, mountune intake, mountune intercooler, mountune rmm,

When I got the car, the hoses were broken off from the evap canister. It ran fine for a few months that way, so I just left it. One day it stalled in my driveway, and it's had this problem ever since. I started getting some intermittent codes (P0087, P008B, and U1007), but they didn't return for quite some time if I cleared them. I've since replaced the evap canister, the solenoid, the HPFP, and the valve up front. The low side fuel pressure has been at 108.8 to 108.9 regularly with the fuel rail pressure running as needed. Now the problem is occurring much less often, but I'm noticing zero psi on the low side most of the time. It runs and starts fine, just not when it's warm and has sat for a few minutes.

Here's what I'm reading off the accessport at idle and at speed.

At idle:

FRP Actual: 604 (558/2275)
Lowside FP Actual: 0.0 (0.0/108.9)
Actual AFR: 14.55 (11.47/43.37) - the high numbers are when coasting down hills in 6th.

At speed (not full throttle):

FRP Actual: 1879 (547/2265)
Lowside FP Actual: 0.0 (0.0/0.0)
Actual AFR: 14.41 (11.61/43.22) - the high numbers are when coasting down hills in 6th.

Thanks for any help in advance.

 

[thomas.mcniven]

Update: This problem occurs whether on the stock tune or the Mountune tune(s).

 

[nickstewartroc]

Have you tried removing/cleaning/looking at the lpfp? It's under the back seat, maybe it's clogged or if it's like a motorcycle I fixed a few years back the screen to keep out debris basically melted down thanks to the ethanol in the fuel

 

[thomas.mcniven]

I'll check that out. It seems strange to me that before it was giving a "Low side pressure is High" code.

 

[Joker328]

Have you tried removing/cleaning/looking at the lpfp? It's under the back seat, maybe it's clogged or if it's like a motorcycle I fixed a few years back the screen to keep out debris basically melted down thanks to the ethanol in the fuel

Yup, seems like it could be the pump or a filter. It's possible that the hot start issue is that the hot engine is causing some of the fuel to vaporize in the lines when it sits for a bit and the LPFP can't pressurize the system quickly enough, so you are getting some fuel starvation.

 

[thomas.mcniven]

Fuel Issues - cutting out on freeway!

Yup, seems like it could be the pump or a filter. It's possible that the hot start issue is that the hot engine is causing some of the fuel to vaporize in the lines when it sits for a bit and the LPFP can't pressurize the system quickly enough, so you are getting some fuel starvation.

So, I replaced the evap canister and all related parts, and added No-Pistons' skid plate at the same time (beautiful!). This issue has died down, but now I'm at 110k miles and I'm getting intermittent fuel pressure loss (high pressure side/fuel rail pressure) drops to 4-45psi, then jumps back up. I've noticed that taking it out of gear and putting it back in usually immediately fixes the problem, almost like the load reduction kicks it back in. I am on my second hpfp, and I just replaced the in tank fuel pump and cam follower, which seems to make it more responsive, but 10 minutes into the drive the problem reoccurred.

I initially noticed the issue on the freeway in sixth gear, after about 15 miles of driving. It usually occurs when it's hotter. Mornings at 80F are usually fine, but the problem reoccurs in the afternoon when temps are higher (90F+). I've moved to Texas from Utah, so I'm wondering if it might be the same problem but a different effect since it's different atmospheric pressure (4000 ft elevation drop). Again, this occurs with AP uninstalled, on the Mountune tune, and on the OTS stage tune.

I've ordered a new fuel rail pressure sensor, and I'm about to fork out the cash for a new high pressure fuel/direct injection pump (fingers crossed that I won't need to spend the $250 on that).

Any thoughts?

 

[TyphoonFiST]

cam buckets?

Whoosh sells them! Food for thought!


https://whoosh-motorsports.myshopif...-fiesta-st-ford-oem-uk-cam-bucket-replacement

 

[thomas.mcniven]

Yep, did that. I called it a cam follower in my post.


Sent from my iPhone using Tapatalk

 

[thomas.mcniven]

cam buckets?

Whoosh sells them! Food for thought!

I got mine from Whoosh. They’re cheaper on Rock Auto now though.


Sent from my iPhone using Tapatalk

 

[TyphoonFiST]

Crankshaft Position sensor? you have to get scan tool and see if it fails by watching the live feed data!

 

[thomas.mcniven]

Would that drop the fuel rail pressure?


Sent from my iPhone using Tapatalk

 

[TyphoonFiST]

You have no stored codes inside the ECM do you? Ive seen CKP sensors fail only under heat or hot conditions....

 

[koozy]

I initially noticed the issue on the freeway in sixth gear, after about 15 miles of driving. It usually occurs when it's hotter. Mornings at 80F are usually fine, but the problem reoccurs in the afternoon when temps are higher (90F+). I've moved to Texas from Utah, so I'm wondering if it might be the same problem but a different effect since it's different atmospheric pressure (4000 ft elevation drop). Again, this occurs with AP uninstalled, on the Mountune tune, and on the OTS stage tune.

I've ordered a new fuel rail pressure sensor, and I'm about to fork out the cash for a new high pressure fuel/direct injection pump (fingers crossed that I won't need to spend the $250 on that).

Any thoughts?

http://www.fiestastforum.com/forum/threads/17138-No-throttle-input-and-stalling-in-idle-no-codes


cliff notes: fuel pressure sensor by the firewall may be the culprit, not the fuel rail pressure sensor.

 

[thomas.mcniven]

Low side usually reads either 0 or 108


Sent from my iPhone using Tapatalk

 

[koozy]

Readings of 100+ during idle/cruising, the low side fuel pressure sensor is bad.

 

[TyphoonFiST]

Low side should read 0-10psi. Readings for 100+ during idle/cruising, the sensor is bad.

I think koozy is onto something....

Sent from my SM-N950U1 using Tapatalk

 

[thomas.mcniven]

Awesome! I’ll run these tests.


Sent from my iPhone using Tapatalk

 

[thomas.mcniven]

P018C


Sent from my iPhone using Tapatalk

 

[thomas.mcniven]

I ordered both sensors for replacement.


Sent from my iPhone using Tapatalk

 

[koozy]

P018C


Sent from my iPhone using Tapatalk

that code in addition to P0148 and P018D further indicates the issue being towards the low pressure fuel sensor.