Engine wanting to stall sometimes

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Engine wanting to stall sometimes

Postby lalojamesliz1 » Tue Apr 20, 2021 8:59 am

What do you guys think it can be? After my engine being on a good 15-20 minutes I've had my engine act like it's going stall, the rpm's are struggling at idle. If I give it gas it seems okay and don't have any codes showing.
I've had this happen before but that was only once. Now it's done it 4 times in the same week. I only drive my all-trac to my job that's 15 minutes away.
Today I was my first day of working mornings instead of nights and on my way home I got compliments from a guy in a suburban and shortly after a guy in a nice s2k. Right after the s2k's compliment I pulled away and I was loosing power and my afr's went from the mid 14's to 16-17 while trying to accelerate. I put it in neutral and let go of the throttle and it started to struggle staying on.
Instead of idling at 1k, it'll be dropping to like 2-400?
Instead of stalling at a busy intersection with the guy that just told me "hey that's a really nice celica" I cut across and turned right then into some parking lot. The problem went away.
I replaced my fuel pump with a denso from rockauto last year maybe but I only drive this car 2-3k miles a year. I inspected my plugs and they are fine.
Does this sound like a fuel pump issue? I do have a little less than a quarter of gas

It's not the same driving to work in in my other cars but I can't chance being stuck in rush hour and having to call a tow tuck :(
I'll have to park her today and until I can figure this out..... :cry:
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91 Celica all-trac gen3 swap (small-med $$$ sponge)
69 mustang 408w (large $$$ sponge)
08 sequoia 5.7L
14 avalon
02 taco dbl cab V6 turd
and a 2 car garage :shoots:
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Re: Engine wanting to stall sometimes

Postby 93celicaconv » Tue Apr 20, 2021 10:15 am

How much different is the engine control from original now? Your referenced AFR - do you control with that or only monitor it? Your AFR is telling you that you are very lean when having the problem. If you are still controlling with an original O2 sensor system, your O2 sensor may be going out on you. And yes, low fuel pressure is also a source problem.
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Re: Engine wanting to stall sometimes

Postby lalojamesliz1 » Tue Apr 20, 2021 5:25 pm

93celicaconv wrote:How much different is the engine control from original now? Your referenced AFR - do you control with that or only monitor it? Your AFR is telling you that you are very lean when having the problem. If you are still controlling with an original O2 sensor system, your O2 sensor may be going out on you. And yes, low fuel pressure is also a source problem.


It's a stock gen3 ecu/engine
This problem just started and it's been running great for at least a couple years. Ah, the 02 sensor.... I replaced it not long ago but I know it can fail soon especially under super rich conditions. It probablyonly has 2-3k miles but still. I'll look up how to test it.
91 Celica all-trac gen3 swap (small-med $$$ sponge)
69 mustang 408w (large $$$ sponge)
08 sequoia 5.7L
14 avalon
02 taco dbl cab V6 turd
and a 2 car garage :shoots:
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Re: Engine wanting to stall sometimes

Postby underscore » Tue Apr 20, 2021 5:40 pm

Trying to diagnose intermittent problems can be a pain. I'd guess possibly a small vacuum leak but I think the gen 3 system is okay with leaks? If it's happening more when warmed up maybe try jumping the fuel pump in the diagnostic box to take the relays out of the equation. I had a defective one in the engine bay fuse box and the engine would start dying randomly once it was properly warmed up.
★ 1991 GTFour RC ~ "Rebel Scum" ★
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
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Re: Engine wanting to stall sometimes

Postby grip-addict » Tue Apr 20, 2021 6:09 pm

OE wiring to the fuel pump ?
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Re: Engine wanting to stall sometimes

Postby 93celicaconv » Tue Apr 20, 2021 6:22 pm

underscore wrote:Trying to diagnose intermittent problems can be a pain. I'd guess possibly a small vacuum leak but I think the gen 3 system is okay with leaks?

Yeah, the Gen 3 3S-GTE doesn't have a MAF (which doesn't like any leaks at all) - it's fuel map is based on a MAP. So leaks should only affect idle speed, but not the quality of the idle, on a Gen 3 3S-GTE. An air leak on a Gen 2 3S-GTE would affect idle quality, without doubt, given it's fuel map is based on an AFM.
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Re: Engine wanting to stall sometimes

Postby lalojamesliz1 » Tue Apr 20, 2021 7:43 pm

underscore wrote:Trying to diagnose intermittent problems can be a pain. I'd guess possibly a small vacuum leak but I think the gen 3 system is okay with leaks? If it's happening more when warmed up maybe try jumping the fuel pump in the diagnostic box to take the relays out of the equation. I had a defective one in the engine bay fuse box and the engine would start dying randomly once it was properly warmed up.



What do you suggest I look for with the pump on? The pressure or just to see if it runs smoothly? I need to get a fuel pressure gauge....
Last edited by lalojamesliz1 on Tue Apr 20, 2021 7:46 pm, edited 1 time in total.
91 Celica all-trac gen3 swap (small-med $$$ sponge)
69 mustang 408w (large $$$ sponge)
08 sequoia 5.7L
14 avalon
02 taco dbl cab V6 turd
and a 2 car garage :shoots:
lalojamesliz1
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Posts: 478
Joined: Sun Jul 23, 2017 3:03 pm
Location: Bakersfield, CA

Re: Engine wanting to stall sometimes

Postby lalojamesliz1 » Tue Apr 20, 2021 7:43 pm

grip-addict wrote:OE wiring to the fuel pump ?


Yup, my car doesn't really have much rust at all and the wiring is in great shape for 30 yrs old
91 Celica all-trac gen3 swap (small-med $$$ sponge)
69 mustang 408w (large $$$ sponge)
08 sequoia 5.7L
14 avalon
02 taco dbl cab V6 turd
and a 2 car garage :shoots:
lalojamesliz1
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Posts: 478
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Location: Bakersfield, CA

Re: Engine wanting to stall sometimes

Postby grip-addict » Tue Apr 20, 2021 8:46 pm

On my car I noticed significant voltage drops when the pump was under even minor load, like boosting 5 psi, so that's why I asked about wiring. But, I misread your post and thought you had an uprated pump when it's not clear if you do.
If your pump IS bigger than stock, then you definitely need bigger gauge wiring to the pump.

It can be hard to tell if it IS a fuel issue or not without a fuel pressure gauge. If you were thinking about getting one, now is a good time to.

I will ask though - how new is your fuel filter?
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Re: Engine wanting to stall sometimes

Postby lalojamesliz1 » Tue Apr 20, 2021 10:48 pm

grip-addict wrote:On my car I noticed significant voltage drops when the pump was under even minor load, like boosting 5 psi, so that's why I asked about wiring. But, I misread your post and thought you had an uprated pump when it's not clear if you do.
If your pump IS bigger than stock, then you definitely need bigger gauge wiring to the pump.

It can be hard to tell if it IS a fuel issue or not without a fuel pressure gauge. If you were thinking about getting one, now is a good time to.

I will ask though - how new is your fuel filter?


I did get a denso stock replacement so I'd imagine the wiring should be okay but I can't say that I'm 100% correct
I'll look into one to diagnose instead of a permanent one since It's stock. Idk, I'll see what's available. Thanks for the tip
As for the filter, it's been a while but it can still hit 10.0 on my wideband. I'll look into that out also to rule it out
91 Celica all-trac gen3 swap (small-med $$$ sponge)
69 mustang 408w (large $$$ sponge)
08 sequoia 5.7L
14 avalon
02 taco dbl cab V6 turd
and a 2 car garage :shoots:
lalojamesliz1
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Posts: 478
Joined: Sun Jul 23, 2017 3:03 pm
Location: Bakersfield, CA

Re: Engine wanting to stall sometimes

Postby underscore » Wed Apr 21, 2021 2:56 am

Check to see if that keeps it from trying to die first, then go from there.

93celicaconv wrote:An air leak on a Gen 2 3S-GTE would affect idle quality, without doubt, given it's fuel map is based on an AFM.


Unfortunately I'm very familiar with that :lol:
★ 1991 GTFour RC ~ "Rebel Scum" ★
Build thread http://www.alltrac.net/phpBB2/viewtopic.php?f=44&t=44216
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Re: Engine wanting to stall sometimes

Postby lalojamesliz1 » Wed Apr 21, 2021 5:00 pm

My all-trac has been doing this for a while now. Not as bad but it's been giving me a smal misfire hiccup while boosting for some time. Obviously my fuel relays are working and I just tested my fuel pump resistor and it's within ohm spec of 0.73.


I'm wondering if it's my fuel pressure regulator????? I saw one of the symptoms of it failing is misfiring! I still have the spare gen3 engine from when I bought the swap to get a e154f transmission and I'm going to swap the fpr's and hope it fixes my issue.
My afr's while cruising are not solid at 14.7 like before when I still had the original gen2 that I blew. It varies from 14.2-14.7 but at idle it's ok. I sold my all-trac and bought it back with the swap installed by some idiots with the original harness and original e150f trans. Got it running properly and just ignored this for a while until I replaced my fuel pump thinking it was that causing the varying afr's but that didn't change it.
Ugh, I guess it's time to start with the fpr.... or should I send the spare injectors to witchunter to get cleaned before I install them.... ah I hate waiting
91 Celica all-trac gen3 swap (small-med $$$ sponge)
69 mustang 408w (large $$$ sponge)
08 sequoia 5.7L
14 avalon
02 taco dbl cab V6 turd
and a 2 car garage :shoots:
lalojamesliz1
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Posts: 478
Joined: Sun Jul 23, 2017 3:03 pm
Location: Bakersfield, CA

Re: Engine wanting to stall sometimes

Postby grip-addict » Wed Apr 21, 2021 5:52 pm

I recently had to replace my FPR on my gen3 3s because fuel pressure wasn't rising with boost. It just sat static... ugh.
I have a gen2 3s that I stole the FPR from. Same issue.
Ended up going with an aeromotive fpr and after that and running bigger gauge wire to my walbro255 it's golden.

Do you get the issue when free revving and taking off from a stop WITHOUT boost?

BTW when NOT boosting you should have more fuel pressure if the FPR's vac reference line isn't hooked up.
Then once boosting, the fuel pressure should rise IF the line is hooked up.

You can also test it by bridging fp and b+ to run the pump when the car is off and then putting shop air (regulate it down to different boost values your engine sees and check the gauge results) on the vacuum nipple of the FPR. Check fuel pressure and you should see it rise when the air's on the fpr nipple.
My gen2 and gen3 FPR's WERE increasing the pressure with the shop air, but they were too slow to respond and were causing tuning headaches.
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Re: Engine wanting to stall sometimes

Postby lalojamesliz1 » Wed Apr 21, 2021 6:08 pm

grip-addict wrote:I recently had to replace my FPR on my gen3 3s because fuel pressure wasn't rising with boost. It just sat static... ugh.
I have a gen2 3s that I stole the FPR from. Same issue.
Ended up going with an aeromotive fpr and after that and running bigger gauge wire to my walbro255 it's golden.

Do you get the issue when free revving and taking off from a stop WITHOUT boost?

BTW when NOT boosting you should have more fuel pressure if the FPR's vac reference line isn't hooked up.
Then once boosting, the fuel pressure should rise IF the line is hooked up.

You can also test it by bridging fp and b+ to run the pump when the car is off and then putting shop air (regulate it down to different boost values your engine sees and check the gauge results) on the vacuum nipple of the FPR. Check fuel pressure and you should see it rise when the air's on the fpr nipple.
My gen2 and gen3 FPR's WERE increasing the pressure with the shop air, but they were too slow to respond and were causing tuning headaches.


What did you need to install the aeromotive fpr? Would you mind telling me what specific model?
I'm considering this to rid of the oem fpr as well.
Right now I'm on a gen3 turbo and didn't want to move away from that and the stock fuel pump works so that's why I haven't upgraded that. I even have a spare ct20b I'm saving. Eventually I'm sure I'll upgrade but for now I'm trying to keep the oem reliability since it's my drive to work car and I have a classic mustang that I need to concentrate my funds into to get that thing running finally.
If I didn't have that mustang......but getting rid of it isn't even a option I'll ever consider.
91 Celica all-trac gen3 swap (small-med $$$ sponge)
69 mustang 408w (large $$$ sponge)
08 sequoia 5.7L
14 avalon
02 taco dbl cab V6 turd
and a 2 car garage :shoots:
lalojamesliz1
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Posts: 478
Joined: Sun Jul 23, 2017 3:03 pm
Location: Bakersfield, CA

Re: Engine wanting to stall sometimes

Postby grip-addict » Wed Apr 21, 2021 6:39 pm

I hear you on that. My alltrac is in the same spot as your mustang while my GTI is my daily and 98% stock car :)

I put in an aeromotive 13109. I also did a racerx fuel rail and deatschwerks injectors, but that's because i'm trying to get more out of a gtx2860r.

The annoying thing with upgrading fuel is the associated AN fittings and lines add up quickly. Where you place your FPR will change the cost a lot. Most common spot I've seen is to place it on the strut tower bar. I put mine to the left of where the wiring loom goes into the cabin because I thought it'd look better... but it was a bit more difficult to run the AN line from the rail to the FPR because of the AC line there.
If you were to hang the FPR from the strut brace, you could just get a 90 degree bend on the return side of the fuel rail (along with the associated metric to AN adapter of course) and run the return right above the fuel rail and routing would be much easier. I think that's why most people place it there.

Here's mine

https://drive.google.com/file/d/14dVWXk ... sp=sharing
https://drive.google.com/file/d/14XUKgG ... sp=sharing
https://drive.google.com/file/d/14ag6tF ... sp=sharing
return
https://drive.google.com/file/d/14dGQ0r ... sp=sharing
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