1G Fuel cut / spark plug diagnose help

[pieceofcloth]

My 1991 gsx is bone stock. Recently I was driving and my car started jerking hard. It starts up perfectly fine and I can drive it around the block and get into boost. After 5 mins it'll start to just like slam /jerk like it has some fuel cut. The idle does not go up and down. It idles perfect. I have an aftermarket fpr and I pulled over and saw the fuel gauge go from like 20-22 down to 0 and back up. My fuel pressure is set correctly with the vacuum line off at 36.5 - 37

My fuel pump was changed a month ago and I forgot to do the fuel filter but did that a week ago. I haven't done a boost leak test cause I can't find my tester at the moment. Here is a picture of my plugs. I did purchase new to go ahead and replace these but I wanted to see if you guys can see or lead me in the direction I should go next.

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The vehicle has always drove fine and this just started recently. I'm thinking I should remove the ecm and send it out. With ecmlink, maybe I cam diagnose it better. No codes or check engine either. Thank you

The gaps on these were at 25, no more. One or two were a bit less. I opened them to 28. And here is a video of it starting up and idling. I'll need to take it around the block to see if it still bucks. Idling/start up

I'm sorry about the video. It drove fine. I put it in 2nd and was trying to hit boost. It cut/bucked and I turned back home. As the vehicle is warmed, you can see I'm having trouble taking off because it won't accelerate. I have to like ride the clutch. When the vehicle is in the garage, it shows how the fuel goes down and up. Could this be the ect sensor? Idk. Thank you in advance

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At 1:05 I'm about to take a right. I go into first, I put in 2nd and am waiting for a vehicle in front me to go further. I accelerate and when I hit 3.5rpm I lose all power. I take a quick right and make another two more rights to pull up into the drive way.

 

[Justin DuBois]

I cant make sense of the video.

Throttle closed switch? over 2K if the TPS close switch is ON the engine thinks you are trying to idle, and it cuts ignition.

 

[Vegas Smith]

Sounds like a fuel pressure issue. Your fuel pressure should not be doing that. Maybe there's a leak in the line?

 

[pieceofcloth]

Sounds like a fuel pressure issue. Your fuel pressure should not be doing that. Maybe there's a leak in the line?

I added a dw300 fuel pump. I didn't add the relay to it. Maybe it's not receiving enough juice and is powering down? I'll check it back there and the sock.

 

[Vegas Smith]

I added a dw300 fuel pump. I didn't add the relay to it. Maybe it's not receiving enough juice and is powering down? I'll check it back there and the sock.

Yeah that's probably it. Larger pumps draw a lot more amps and stress the stock wiring. You gotta do the whole relay rewire when putting in bigger pumps

 

[pieceofcloth]

This was a new sock. And the inside of this tank looks nasty. I'll need to attend this down the line. I have the relay, just need to order me a longer power cable(proper gauge). Thanks

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[turbomister2]

Here to see what resolves this issue
My car randomly has started this same behavior
Sometimes perfect sometimes will “hit fuel cut “ symptoms

 

[pauleyman]

Fuel cut is violent. Is it violent?

 

[pieceofcloth]

Fuel cut is violent. Is it violent?

It's like my car is driving fine , then slams with 0 power. It makes me "look" like I'm new to driving. Like I can't drive stick. I lung forward in my seat cause the vehicle just doesn't perform/go.

Yeah that's probably it. Larger pumps draw a lot more amps and stress the stock wiring. You gotta do the whole relay rewire when putting in bigger pumps

Purchased some 8 gauge awg wire. I'll update here soon

 

[DSMPT]

Be cautious to drive until you fix the issue or may be better not to drive. Once something similar happened to me after replacing the fuel pump with aftermarket one and it ruined forged pistons.

 

[pieceofcloth]

Be cautious to drive until you fix the issue or may be better not to drive. Once something similar happened to me after replacing the fuel pump with aftermarket one and it ruined forged pistons.

I've got it parked at the moment. The 8 gauge awg cable should be in soon and I'll rewire the fuel pump with a relay. Thanks

 

[We're on Boost]

It looks to me though like your fuel tank is just full of rust, and it's clogging things up, like the sock, the fuel filter probably, and maybe the injectors.
Is it rust in post #8? Or is it just a really yellow light messing up the picture?
What did the fuel filter look like when you changed it a week ago?

 

[pieceofcloth]

Fuel filter was clean and worked properly. The last pump which was a walbro was pretty nasty. I replaced it because it was screaming loud. I have a video within my recent post on my 1991 gsx vehicle account. The vehicle never did this buck thing before. The new pump has been in there for maybe a month. It just started doing this last Friday and I haven't figured it out or messed with it since today.

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I don't think it's the sock, Filter nor injectors because it doesn't misfire.

It looks to me though like your fuel tank is just full of rust, and it's clogging things up, like the sock, the fuel filter probably, and maybe the injectors.
Is it rust in post #8? Or is it just a really yellow light messing up the picture?
What did the fuel filter look like when you changed it a week ago?

I use one of those streamlights. It's a white led shine. That should be rust and fuel together in there.

 

[We're on Boost]

The new pump has been in there for maybe a month. It just started doing this last Friday

Was it ok for 3 weeks on the new pump without the rewire?

 

[pieceofcloth]

Was it ok for 3 weeks on the new pump without the rewire?

Great question. I don't drive it much but on the weekends. Probably 6 miles per, in a circle. I changed it and didn't drive it for a week or two cause it was raining or cause I don't actually have anywhere to go . On the third week I needed to go see some one and on the way, it started. I changed the filter the following week. I did drive it though and never had the problem with the new pump.

My house from the San Jacinto monument is a good 7 miles, so 14 in total in one weekend.(week2)The next weekend it started acting up, I didn't get but 3 miles far and had to turn around.


Yes it could be from lack of power and possibly dirty/clogged injectors from the tank. Maybe I should go ahead and remove the tank and get it cleaned, clean the injectors and get ecmlink installed already. But yeah, my car doesn't misfire. It just bucks at random acceleration. It doesn't have to be in boost.

 

[Justin DuBois]

Running MAF? Is your BOV recirculated? leaky recirculating hose or vent to atmosphere would cause bucking/rich condition.

 

[pieceofcloth]

Running MAF? Is your BOV recirculated? leaky recirculating hose or vent to atmosphere would cause bucking/rich condition.

Yes, 1g maf. The hose looks fine and nothings is pinched.

 

[danl]

Is the o ring that seals the pump output to the sender in good condition and not crimped?

 

[pieceofcloth]

With the dw300, it doesn't fit in snug like the walbro. I have to cut the metal tube an inch or so and use a hose to connect the pump to sender tube

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[habitatguy187]

I had similar issues a long time ago and it turned out to be the ecu. However, I would swap that noisy 255 back in first and see how it responds. It might be that the new pump is bad. I had a nib aeromotive 340 crap out after about 10 days

 

[pieceofcloth]

I had similar issues a long time ago and it turned out to be the ecu. However, I would swap that noisy 255 back in first and see how it responds. It might be that the new pump is bad. I had a nib aeromotive 340 crap out after about 10 days

I also believe it may be the ecu. I threw away that loud pump. I did the rewire and now my vehicle only cranks. No fuel gets sucked up threw the lines. I put my pump to the battery and it works fine. I checked my grounds with volt meter and they're fine. I get power to the yellow wires when key forward but not the black and white cable that everyone says is the trigger. Maybe it gets power once the car is on.


My fuel gauge level is no longer working now. It doesn't move when key forward. I just put new gas to make sure there is some in the tank to move the level.

I plugged the old harness that was spliced back up and even tried to remove the rewire to get it back to stock, and I still have the same issue.

BNW from car side is on 86
BnW from pump side is on 87
Chassis ground on 85
12v power with inline fuse on 30

Yes my inline fuse works and yes I receive 12v. I originally spliced the yellow cause I read 90s 1g version article then, i read a 91 which says use BNW cable so i hooked the cables back because i had cut it from the harness. That's why you see the connector. Yes my relay works, i tested with volt meter and even replaced it. Im pulling the ecu out tonight.

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[pieceofcloth]

I have continuity from pump to pump harness for power and ground. The same on vehicle side harness. I grounded the yellow wire and my gauge did not move. Maybe it shorted when I hooked it to the relay, the first time?
I was going to check again and see if my level is not stuck or if the cable isn't broke. I removed my fuel line and fuel came out so I know my pump is working.

I need another set of hands to turn key so I can check fuel pressure gauge under the hood. Could be dirty injectors, bad ecm and bad sending unit now. Idk. This all happend instantly, this is a bone stock vehicle.

 

[pieceofcloth]

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I can't tell. This is a non Eprom so I'll need to get it converted or find one for my vehicle with ecmlink already installed.

 

[pieceofcloth]

I have a 1990 ecm that was awd as well. Can I put this in just to see if it's my computer? I read I just need to swap a single wire. Can I not swap the wire and try to see if it'll work?

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This had ecm link but I swapped it to my fwd eclipse. I had it tested and they said it's fine. Just wondering if I could just use this computer to test.

 

[steve]

Sure, the pins to swap are 6 and 14. You release the pins from the connector and exchange them.

https://www.dsmtuners.com/threads/how-to-identify-ecu-pin-numbers.246467/

Remember to take a log first and save it so you can restore the setting for your other car abd then reset everything to stock and get a log of it acting up and post it here.