Throttle cut out at 3500 rpm

[Piranahbite]

Hey guys! Here with a question for yall, my 87 mustang runs like a champ, has a cam nock, but still runs great. A month or two ago, i was driving my car home and i laid the hammer down at a couple stop signs and at around 3000 rmp, the engine seemed to hit a rev limiter of some sorts, not reving, but more like hesitating for a sec, then continuing up the rpm range, but the issue only occurred when trying to exceed 3000 rpm. I shut the car off and checked all my plug wires, coil wires and they were all good, drove it around and the problem dissappeard. A second time i went and got gas and that solved the issue. This time, its doing it pretty bad, i was tacking it out practicing for my NHRA race i got comin up ( im racing top the cops at sonoma) and at 3500 rpm it seemed to hit a revimiter that cut the ignition out till it got to about 3200 rpm then attempted to get past 3500 and failed. I shut the car off and it seemed to go away for 2 or 3 pulls then started again. First time it was a lil hesitate, then got more noticable at about 4000rpm dropping a couple hundred rpm but never climbimg passed 4000. Tomarrow ill go get gas and see if its a fuel starvation issue. But I dont think iv done enough driving to warrent it being a lack of fuel in the tank (no gas guage to tell) maybe its an injector? I have a new cap and rotor and plugs n wires that I installed 10,000 miles ago. Shouldnt be bad yet right? And finaly, yes, i checked all my ignition wires again and evreything is plugged in. And it will rev past 3000, and 4000 rpm WITHOUT hesitating when clutch is pushed in or is in neutral

 

[Piranahbite]

Just got back from testing the car again. Went out drove for about 5 minutes with no issues then decided to do a pull since the issue starts at 3,000 to 4,000 RPM and issue was still there the car stutters and hesitates just like it did last night. Issue only occurs at 2/3 throttle to Full Throttle and at 2,00 3,000 and 4000 RPM give or take a couple hundred only upon acceleration. Went to the gas station put 8 gallons of gas in the 15 gallon tank and issue has not reoccurred. I took a video of the issue me and my dad ruled it to be a fuel issue, maybe there's something wrong with my pickup sock or pick up tube.Video 1 Video 2 my dad went through the same issue with his 72 Cutlass. His car would hesitate only in left turns he replaced a carburetor and went through his whole fuel system since he thought his engine was being starved but it turns out it was his distributor. I feel that since adding gas made the issue go away it's not an ignition related issue. But of course adding gas to the tank is way too simple because I have ran the car out of gas more than once and it performs like a champ until enpty. So it is an intermittent issue but an issue none the less I hope im not the only one to have experienced this and theres a simple fix to this. Thanks for any help folks!

 

[Noobz347]

Things that come to mind:

What is the engine build? Any mods? How long ago?

The fuel tank needs to come down but not just to check things out. Plan on replacing the pump, pickup, and sock. This will confirm/deny your suspicions and changing the pump is just cheap insurance, particularly if you find nothing visually wrong with the sock or pickup.

Check your coil saturation. You should see 14 +/- volts with the engine on. Have somebody rev it to the 4000 territory and ensure you don't have a voltage drop.

Pull your spark plugs and [read] them or post pics of each one and their position.

 

[Piranahbite]

Will do! I wont get to it till im low on gas (lifting and dropping that tank sucks when its full) its a stock 1987 N/A 2.3 no mods, just a removed air conditioner belt and a couple degrees of timing. Replaced the fuel pump and sending unit and pickup sock around 20,000 miles ago (car has 123,000 miles ) when i got the car, it was the reason why it was parked.

 

[Noobz347]

It's good that you mentioned that. Put your timing back to the stock setting at least until this is sorted.

 

[Piranahbite]

It's good that you mentioned that. Put your timing back to the stock setting at least until this is sorted.

Okay, well.... i never retarded the timing.. but, i have noticed my fuel pump wich usually sounds like EEEEEEEEEEEE now sounds like EEEERRRREEEEERRRRREEEERRRR. Like its pulsing or somthing. Wich im sure is not normal. And now the stutters are more frequent even with a full tank. It still primes when you turn the key. It also sounds like its pulsing from in the car, like the pump motor is bad.

rock auto had a deal on fuel pumps so i bought one! hoping to have it by Monday so I can race on Friday

 

[Piranahbite]

Alright yall, iv had quite the weekend, i did a hundred mile trip, and the car died. 90% sure it was the fuel pump. I replaced it outside a taco bell roadkill style. And the car ran great for a day, today on my way home it started the hesitations again, at 2,000 and 3,000 and 4,000 rpm and sometimes in between them. Im pretty sure the old one was bad (video of it), but maybe i have another issue causing the hesitating? Distributor? Ignition coil? Injectors?

 

[Piranahbite]

Heres what im thinking. Im thinking i have a bad fuel filter, my taks kinda dirty and the old ones been on for 30,000 miles, i feel like its being restricted by all the crud that the filter caught, so ill get a new one and see if the problem goes away. Issue also stops when you fill up the tank just like the old pump

 

[Piranahbite]

hey guys!!!! I got my car running right. I'm 90% sure I fixed it. I have a power steering fluid leak and it completely soaked my spout connecter, I cleaned it up and the issue hasn't returned! also, I did race at the NHRA race at sears point raceway on Friday and Saturday if any of you guys were there. im part of the top the cops program, Friday night I broke out and ran a 20.05 with a dial in of 20.15, and Sunday afternoon I beat the guy (police officer) and ran a 20.38 with a dial in of 20.05 here's a video of the pass from friday were I broke out, im working on getting my second run

 

[Piranahbite]

Update, issue is still happening, puel pump sounds like its going to take a crap, and i think its either fuel pump still, or somthing ignition wise, distributor or speed density sensor. Thats what im thinking

Im aslo getting codes 34, and 77

 

[Piranahbite]

Still having this issue, its less common now, but it still is happening... anyone think it could be my fuel pressure regulator?

 

[Piranahbite]

OK, so, um, yea, issue still happens, just happens less, it happens when I make left and right turns or when I lose about 3 or 4 gallons of gas..... I think its my fuel pump... again.... I feel like my pumps not reaching a point in the tank that consistently full of fuel, or the pump itself is too short and not reaching fuel. i replaced it with a universal AutoZone pump but still use the original fuel pump holder that didn't really fit right cuz the pump was the wrong size for the cage (i was stranded 100 miles from home) and i feel like a really good piece of evidence was when I tried to get sideways I tried to spin her to the right, and the engine starved itself of fuel and the same thing happened to the left, and this totally goes against everything I just said but, it proves that the engine is starving of somthing, liquid. i think my possible culprits are the fuel pump, or pressure regulator... any opposition?

And then later in the day with even less gas in the tank (cuz i drove another 50 miles) it gets sideways no problem without any stalling whatsoever ( after the fact the idle turned up to about 1500 rpm, car usualy idles at 900 rpm

 

[AeroCoupe]

The baffle in the tank may have broke loose as well but my money would be on the Autozone pump.

https://lmr.com/item/LRS-9350B/1986-97-Mustang-190-Lph-Walbro-Gss242-Fuel-Pump

Do not be scared to run a 190 lph pump as it will be fine.

 

[Noobz347]

Is that pump an "Intex" by chance? They're only good for one thing: Putting in a pillow case and hitting somebody with it. I tried using one as a paper weight... It failed.

 

[Piranahbite]

The baffle in the tank may have broke loose as well but my money would be on the Autozone pump.

https://lmr.com/item/LRS-9350B/1986-97-Mustang-190-Lph-Walbro-Gss242-Fuel-Pump

Do not be scared to run a 190 lph pump as it will be fine.

I wont! Im also going to drop in a turbo coupe motor, would a 190 lph pump be better fit for that?

 

[Piranahbite]

Is that pump an "Intex" by chance? They're only good for one thing: Putting in a pillow case and hitting somebody with it. I tried using one as a paper weight... It failed.

Nope, well... maybe, its some orileys universal fits 100 vehicle pumps (precision fuel pump) thing didnt fit right and i had to modify my original pump hangar to fit it

I either bought the master pro pump 50gph or the precision pump 33 gph

 

[AeroCoupe]

Both are garbage so get a Walbro. You need to run a calculator to see how much hp the 190 lph will support in a boosted 4 cylinder application. I believe factory still used an 88 lph pump on the Turbo Coupes.