Tech / General Engine Is your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!

running rough after possible overfuel hydrolock?

Old 06-13-2019, 06:01 AM
  #1  
Senior Member
Thread Starter
iTrader: (5)
 
ownor's Avatar
 
Join Date: Sep 2006
Location: Austria
Posts: 950
Likes: 0
Received 0 Likes on 0 Posts
Car: 84 TA / 89 Formula
Engine: LS1 / L03
Transmission: T56 / 700R4
Axle/Gears: 3.73 / 3.27
running rough after possible overfuel hydrolock?

ok guys i have some problems here with my stockish L03 in the Formula. wanted to get it up and running this year after it's been parked for some years due to slight body damage caused by my beloved neighbor and a busted AT cooler in the radiator (ATF and water mixed). i have fixed the latter so far, then on the first longer drive i ran into a problem of very intermittent low fuel pressure (had that happen rarely over the past 10 years). drops to somewhere around 7, 8 psi from my set 15-16 psi. TBI return port blocked in that condition the pressure goes over 40 psi so likely no issue with the TPI (ACD EP241) pump.
so went and changed the FPR membrane now since it looked a bit ripped.

when i removed the inj pod for some reason there was a lot of fuel pouring out that only stopped when i opened the gas tank cap (which as most times for me, was under pressure). so there was some fuel leaking down the TB bores. after putting everything back together and trying to start, after short cranking it stopped and guess it kinda hydrolocked on the fuel and wouldn't turn any further
so let it parked with TBs open at WOT to vent the intake for some hours, then tried again at WOT/flood clear mode. turned over and would eventually start but when I closed the throttle on startup there was an intake backfire and a fireball where i shut it off a little scared

now after some days parked i tried again today and it actually "ran" (rough, but still) for about a minute *with disconnected injectors* before i shut it off because i thought it would be much too lean that way. i found that pretty strange though?

then i reconnected the injectors and got it to run finally (although i had to use flood clear mode to start it again), at around 30C CTS the WB (in Y collector) reported 13ish AFRs, NBO2 (driver side header) 980ish mV but it ran quite rough and didn't want to idle below 50-55 kPa MAP. all sensor values look ok, fuel pressure is good and constant, shut it off after another minute or so. header primaries got about the same heat from feel. plug cables are all wired up correctly (little tweak done to routing before) and i didn't change anything else...

confused now, is it likely there's some damage to the engine from this "hydrolocking" with fuel?
i guess next step would be pulling the plugs and checking compression?
ownor is offline  
Old 06-13-2019, 08:38 AM
  #2  
Senior Member
Thread Starter
iTrader: (5)
 
ownor's Avatar
 
Join Date: Sep 2006
Location: Austria
Posts: 950
Likes: 0
Received 0 Likes on 0 Posts
Car: 84 TA / 89 Formula
Engine: LS1 / L03
Transmission: T56 / 700R4
Axle/Gears: 3.73 / 3.27
Re: running rough after possible overfuel hydrolock?

here's an EBL log attached.
600-800 rpm idling at around 50-55 kPa MAP as said but pretty rough as you can see in the jumpy RPM signal.. NBO2 960-980 mV, WBO2 only comes in at about 20s runtime and goes from ~14:1 to 12.8:1 at about 55sec runtime.
what do y'all think?
Attached Files
File Type: csv
ownor is offline  
Old 06-13-2019, 11:08 AM
  #3  
Junior Member
 
RJ IROC's Avatar
 
Join Date: Apr 2013
Location: Saint Louis, Missouri
Posts: 52
Likes: 0
Received 0 Likes on 0 Posts
Car: 1985 Camaro IROC-Z
Engine: 383 HSR Comp XFI280HR Profiler 195s
Transmission: T5
Axle/Gears: 3.73 Posi
Re: running rough after possible overfuel hydrolock?

I wouldn't worry about the damage from trying to crank the car with fuel in it. Although I may be saying that just to put you at ease...

After my first night at the strip, I lost the intake rocker to cylinder number one. I didn't tighten the poly-locks quite enough. I drove the car for 20 minutes like that, with fuel continuously being sprayed into the runner. I ended up towing it back to another place, where my tools were. I had to start it to pull it into the driveway. It sat for a couple of days, and when I pulled the spark plug, I got a huge stream of gas out.

If my engine survived that, you're probably fine.

Take your injectors out, blow the injectors out both ways with carb cleaner to get all the gunk out. I would assess the running condition after you get your fuel leaks fixed.

With your fueling situation taken care of, check the base advance with a timing light.

I'll take a look at that log when I get back home....If I can remember!
RJ IROC is offline  
Old 06-13-2019, 12:02 PM
  #4  
Senior Member
Thread Starter
iTrader: (5)
 
ownor's Avatar
 
Join Date: Sep 2006
Location: Austria
Posts: 950
Likes: 0
Received 0 Likes on 0 Posts
Car: 84 TA / 89 Formula
Engine: LS1 / L03
Transmission: T56 / 700R4
Axle/Gears: 3.73 / 3.27
Re: running rough after possible overfuel hydrolock?

Thanks for the input RJ. What worries me most is the running engine without the injectors connected now, just like in the video. I just pulled out of the garage that way.. exhaust smoking a bit and also from around oil dipstick or CCV tube to air cleaner..
I don't get it, is it running on engine oil now? 🤔😅
ownor is offline  
Old 06-13-2019, 03:40 PM
  #5  
Junior Member
 
RJ IROC's Avatar
 
Join Date: Apr 2013
Location: Saint Louis, Missouri
Posts: 52
Likes: 0
Received 0 Likes on 0 Posts
Car: 1985 Camaro IROC-Z
Engine: 383 HSR Comp XFI280HR Profiler 195s
Transmission: T5
Axle/Gears: 3.73 Posi
Re: running rough after possible overfuel hydrolock?

Originally Posted by ownor View Post
Thanks for the input RJ. What worries me most is the running engine without the injectors connected now, just like in the video. I just pulled out of the garage that way.. exhaust smoking a bit and also from around oil dipstick or CCV tube to air cleaner..
I don't get it, is it running on engine oil now? 🤔😅
If it's running without the injectors plugged in:

1. Bad FPR diaphragm. That could explain your fuel pressure situation. If the diaphragm ruptures, the fuel goes through the vacuum line into the intake. That's kind of a bonus. You get pressure that's regulated in relation to vacuum, and if the diaphragm ruptures, the fuel gets burned instead of spewing all over the hot engine.
2. Sticky injectors
3. Leak on the top side of the injectors

I'm inclined to think that the FPR diaphragm is bad. That would, easily, introduce enough fuel to make an engine stumble and run. I'd start there. Smoke from the exhaust would indicate a rich condition, from a few cylinders receiving too much gas. That would also explain why your NB readings are high. Values that high indicate a rich operating condition, for stock engines anyway.
RJ IROC is offline  
Old 06-13-2019, 06:01 PM
  #6  
Senior Member
Thread Starter
iTrader: (5)
 
ownor's Avatar
 
Join Date: Sep 2006
Location: Austria
Posts: 950
Likes: 0
Received 0 Likes on 0 Posts
Car: 84 TA / 89 Formula
Engine: LS1 / L03
Transmission: T56 / 700R4
Axle/Gears: 3.73 / 3.27
Re: running rough after possible overfuel hydrolock?

Supposedly, my crankcase full with 10-15l of oil diluted fuel (or was it the other way round?) will cause the engine to run without injectors 😅🤯 sucks in oil/fuel from bottom.. drained and pulled black plugs.. will refill with oil and measure compression tomorrow.
ownor is offline  
Old 06-14-2019, 06:22 AM
  #7  
Senior Member
Thread Starter
iTrader: (5)
 
ownor's Avatar
 
Join Date: Sep 2006
Location: Austria
Posts: 950
Likes: 0
Received 0 Likes on 0 Posts
Car: 84 TA / 89 Formula
Engine: LS1 / L03
Transmission: T56 / 700R4
Axle/Gears: 3.73 / 3.27
Re: running rough after possible overfuel hydrolock?

Runs good now again after an oil change, plugs pulled and cleaned

Thanks for your inputs RJ. So this ghost-fuel issue, running without injector connected, is solved

On the FP dropping, I can't really pinpoint the problem. For one, it only happens very intermittently but wants to die all the time and has no power when it happens, and then sometimes all of a sudden clears up again and runs just fine.. Not really related to driving style, temperatures, weather or anything (although, I only drive it on nice summer days mostly). But this is always related to an FP drop. Since I checked pump pressure once in an FP drop phase and it seemed to be fine with TBI return blocked, that rules out the pump. That lead me to replace the FPR diaphragm (which is where some (I thought much less than it was, weird..) fuel found its way into the oil now)).
BTW FWIW, the Standard Motor Products Kit I bought (PR131, not cheaper T-series) for the TBI had a spring in it that would only let me set my max fuel pressure in the 14 psi range, whereas the stock one goes up to about 18-19 psi. So I guess if you don't measure or have made your FPR adjustable before, you'll have lower fuel pressure than before when using it (I only used the gaskets and membrane along with some new o-rings and injector filters).
ownor is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
IROC406
TPI
16
08-28-2018 10:50 AM
fastrs1891
Tech / General Engine
9
07-05-2010 12:23 PM
Grants89iroc-z
TPI
39
01-23-2010 02:56 PM
hgffrank
Tech / General Engine
3
08-19-2007 09:35 PM
305RSlc
Tech / General Engine
9
10-11-2004 02:46 PM


Thread Tools
Search this Thread
Quick Reply: running rough after possible overfuel hydrolock?


Contact Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: