hot car no-start issue

[Reaper1]

After writing this I realized how long it is!! Oops. I just didn't want to leave anything out. If anybody can make any sense out of this mess, then I'll be greatful. I'm confused and lost in the jumble and have found myself maybe shortsighted as to what the issue could possibly be. Thanks for your guys' time if you do read this and can make any suggestions based on this information.

I've taken several steps to ensure that my car runs within the lower limits of the heat range. My radiator is only a few years old. I'm running about a 70/30 mix water/antifreeze with Water Wetter thrown in there too(Florida, so cold isn't much of an issue ). The fan is a modified V6 unit with the shroud covering all of the back of the radiator, so any air it sucks HAS to come through there. I run a 195* T-stat with a bleed hole drilled in it(I've found the car runs better on the higher t-stat). I also run a pretty large oil cooler. The only downside to the oil cooler is that it doesn't have its own fan and that it is stuck behind the intercooler, but it does work, especially at speed! I've also made a custom fiberglass apron that goes from the front nose of the car to the core support so that any air that gets in the nose hase to go through the radiator support. I've also kept the lower core support air dam in place.

So far, if the car is moving, it's fine. Even in traffic it does well as far as heat is concerned. The issue I'm having happens after the car is shut off! It seems like it heat soaks the fuel rail and causes a vapor lock condition due to the low pressure in the rail not being able to keep the fuel from boiling. Sometimes when this happens, if I prime the pump and then try to start the car(and it fails) you can hear gurgling in the tank, like air being pushed through the return line. Once that happens, it's taken me up to 20 minutes to get the car started(killing the battery in the process, not to mention bearings, although usually I see oil pressure if I have to crank on it more than three times!!!)! :

As an experiment I started using an infrared thermometer on stuff under the hood when the condition presented itself. I found that the fuel rail was in the 145*F range and the intake was over 200*F(these are obviously surface temps, but internal temps would probably be close to the same). I also found that while the car was running the fuel rail was about 112-115*F and the intake was pretty hot still at around 160*F.

So, seeing that the temps were MUCH lower when the car was running I tried to come up with a way to block heat transfer as fast and as dramatic. I came up with using some sort of heat sheilding wrapped around the rail. I was going to use some stuff by DEI, but the local speed shop was out. So, I made my own! I used plumbing insulation wrapped with aluminum HVAC tape. It works OK. Not as well as I'd hoped. It does take longer to heat soak the rail, but not enough(or so it seems). I wasn't able to wrap the very ends or the areas where the FPR is, so those are still exposed. Opperating temps are about the same, but it does take a while longer to raise the temps of the rail to what I was seeing unwrapped.

I also put a fuel pressure gage on it to make sure I wasn't bleeding pressure down while the car sat. What I found kinda startled me. I had set my fuel pressure based soley on my A/F's read by my WBO2 at WOT with no help from the water/alky injection. I had gotten them in the 12.2-12.0 range. However, my static fuel pressure ended up being 32psi!! With the vacuum of the engine it was down to 24psi! Once the engine shut off, it stayed rock steady at 22psi. The issue repeated itself while the gage was on the car, but no gurgling could be heard from the tank, so I don't know if the fuel was still boiling or not. I did have to raise the pressure to 40psi to get the car to start though! Seeing this made me rethink my base pressure though...A/F's be d@mned...I need to be able to drive the friggin car! I raised it up to 35psi(this lowered my A/F's to about 11.8-11.7 and the car seemed to actually like it better as it *felt* stronger). The issue seemed to be mostly solved at that point. I drove the car for a few days without incident, then it started again! I've got to throw my pressure gage back on it to make sure my fuel pressue hasn't moved on me(I don't think it has becuase my A/F's are still the same at WOT).

Last night when I went to the track I never shut the car off! I was affraid to simply becuase I didn't want to run in to that embarassing no-start problem. I think letting it run did help the car stay consistant as it ran 99-98mph all night, running exactly 99.25 TWICE!!

Anyways, this problem has me stumped. It never did this until it got pretty hot outside(90* ambient temps or hotter). I did try a different *known good* hall effect, just to try and rule out a heat vs. electronics problem, but it made no difference. No codes besides the lurking one for the stinking "injector driver 2" are present(running FWD Stage 5 cal). : I've cleaned the harness plug at the rail, and also the hall effect plugs. I suppose I need to clean the other harness plugs as well, but the injector wires go straight from the SBEC to the harness plug at the head. The +40 injecors are *brand new*(they were never installed in a car until I put them in this one about a year ago or so). I suppose I *could* have a bad injector harness, but I've tried the wiggle test and that yeilds nothing. It only throws the CEL on the highway while cruising. At 65-70mph the car has a miss to it that I can watch on my WBO2...it acts like a lean pop as when it happens the A/F's go up to over 15.5, the computer seems to catch it and they shoot back down to 13.7-14.2, then even back out. It's really only at this load condition that it happens. It seems like a part throttle, mid-load issue, and anywhere between 12-0vac at part throttle the car will pop and buck, like it has no clue what to do!

Anyways, sorry again for the length, but I didn't want to miss anything. If somebody can help me with this I'm going to be VERY greatful!

[turbokid]

Wow that was a lot.
I am guessing from your mods you are running a walboro 255 pump?
Now when it has this no start issue, have you checked if you have spark?
Can you check what your fuel pressure is when it decides not to start?
I wonder if your injectors are getting hot.

[Mystryguy]

its a very good chance its your pump. I had this happen when my dad was driving the car... he assumed the same thing and put a cooler on the fuel to help out but its was still a crutch for the main problem. I changed the pump and never looked back. DON'T rule it out if its a walbro because ive been thru ALOT of walbros and they arent very high quality.

[turbokid]

^thats kinda what I thought.
Maybe the pump is getting too hot and poopin out on you

[Reaper1]

Yes, I am running a Walboro.

I don't think it's the pump as #1, I ALWAYS prime it at least once before I start it, and #2 you can hear the pump running as the engine is turning over.

Fuel pressure WAS 22psi when I checked it the first time when I decided I'd had ebough of it. Static pressure(without the vacuum line hooked up) was 32psi. Dynamic running pressure was 24psi at idle.

After seeing this I bumped the static pressure up to 35psi and it seemed to clear the problem up for a while. Now it's back. I checked my A/F's on my wideband after my initial change of base static fuel pressure at WOT and they were in the 11.7-11.8 range. This has not changed, so that makes me beleive that the static pressure has not changed, but I'm going to check it anyways.

I've also got a few other things I'm going to attempt to do as suggested to me by another board. These things are electrical as far as making sure my connections are clean and free of oil, ect.

I'll report back when these thigns are done. In the mena time, keep the suggestions coming as I REALLY want to fix this thing!

[turbokid]

You didn't answer the question of whether you have any spark.

[turbo minivan]

my car seems to do this same thing sometimes. sometimes ill drive it just to the gas station up the streetand it wont start again for about 10-15 minutes (once its cooled a bit) my engine dosnt run hot or anything, and i have spark when its doing this, but whn it does it, i usualy cant hear my fuel pump (walbro 255) prime. my fuel pressure does rise to about 35psi after cranking once or twise, but quickly drops to zero after i stop cranking it. usualy my AFPR will hold pressure for at leat 5 minutes after priming/running and i run stock (or close to stock) fuel pressure. so all i can seem to think is the pump as well.
do you realy think its just the pump being too hot and getting weak with the heat?
its not a very old pump.

[Reaper1]

Turbokid, I checked spark this evening when I got the problem to repeat. I DO have spark. Fuel pressure is also steady while the issue is happening at about 30psi. My fuel pressue does not drop off after the engine sits. As a matter of fact, it actually GAINED pressure! I attibute this to expanding fluid as it heats up.

Anyways, TurboMinivan, my issue is different than yours as mine keeps the pressure.

After doing all these tests we finally tested the last thing you should before you condemn it...the computer. First we made sure the car was messing up. Then we changed first to a Super 60 computer. While it wasn't the best thing, the car DID start the second try! Now, the idle SUCKED, but the thing is that it did start. Next we changed to a STOCK '88/'89 SBEC turbo computer(TI or TII unknown!!)..the car fired right off and idled PERFECTLY!!(this was even with the 3-bar MAPn and +40's!)

So, it seems that the cal I have has some sort of issue in it that simply doesn't like to start the car when it's hot. Guess I'm calling my vendor... I know it casn be resolved, I just hope it can be done fairly quickly.

[glhs496]

Hey Reaper, so what happened?

I am having the same problem, although it's not as hot here in MA.

FWD Stage5 Cal/+40's/3 bar/MP BV Head/Indy IC/new Turbonetics T3T4 Turbo/3in exhaust.

With the fuel pressure cranked to 60psi static it starts better, but I'm losin alot of HP.
I lowered it down to 48 psi, (my best dyno runs on the old turbo were at 43 psi.)

It will not start hot. I have to wait ten minutes. I get spark, I put on a new HEP, I have cleaned and tightened every ground on the car, I swapped injectors, I have a fuel gauge on the rail so I can see I have fuel pressure.

When I get out my old MP T2 stage 2 computer, it fires right up in half a crank!!!

When I put in my super 60 computer it acts just like the FWD computer.

Anyone have any ideas?

I can run the car on the road course cause you start it, drive it and park it. I took it to the drags, and like you pulled into the staging lanes, shut it off, waited for the line to move and kept it on. It did do 105 so when it's running, it's running okay. (I'm down 5 mph from a couple years ago).

Hard to go to the dyno, or attempt to get an inspection sticker with this problem.

The idle is pretty crappy too.

[Reaper1]

Well, right now I'm awaiting my new cal chip from Cindy. Supposedly she's supposed to ship it tomorrow. I think I'ma call her and remind her again! LOL I know she's buisy, so I'm just going to keep claaing until I get it! Right now the car seems to be doing the same thing, but it's slightly better.

I don't know if I put this info in this thread, but I did raise the static fuel pressure. It was at 32psi before. I now have it at 35psi. While it's not perfect it did *help* the issue and it didn't mess my tuning up much, if at all. I think the car actually GAINED power!

When my car has the issue, if I go to start it and it fails to start, I can hear gurgling in the tank, like air being forced through the lines for the first few attempts at starting it. If it fails to start after about the third try, if I wait and count to 60 seconds(using the one-thousand technique) I have about a 60% success rate with that. If I do it too soon the car most certainly won't start. If I do it after that, it may try to start, but fail and I have to start over.

I'm hoping the weather stays hot enough to test the new cal I'm getting. I suppose we'll see!

From my experience so far, get a hold of Cindy and tell her your issues. She can have your cal revised and hopefully fix your issues. You will have to get a code off the chip in your computer so she can look up which cal you have(there are different varients of the S5 from what I've been told).

I think it's odd you are having issues with the fuel pressure you are running. Mine will start almost every time if I raise the static pressure to 40psi, but it completely frags my tune.

I will say that I redid my grounding system on the battery. I had a TON of things gorunded to the battery terminal and it looked sloppy and was an EE's worst nightmare! So, I went and took all that apart, cleaned the battery terminals REALLY well, then cleaned the exposed wires with electrical cleaner(I'm running an aftermarked battery terminal). When I put it back together I used a little dielectric to ehlp prevent water intrusion and corrosion. I also installed a remote brass ground block. Now all my "battery" grounds go to that and it is directly gorunded to the battery via a 10ga wire. So far it works well! The car seems to turn over better as well. Just something else to think about....

[phantomrt]

I recently replaced the fuel pump in a '91 Daytona and my '92 Lebaron. The vehicles' original pumps are Walbros. Just FYI.

Most cars I have is having vapor locking issues. My TT stealth, and both my T-1's. A friend of mine just had his IROC R/T here yesterday and it also had a very hard time starting after a 15 minute heat soak. My cars always start even on the hottest days, but they run crappy until the air is purged out with cool fuel. Even my 2.7L Intrepids had the issue. Very annoying. I don't know what it is, but its must be something to do with today's gasoline formula. Lots of alcohol in it or something? You can verify vapor lock by hitting the schrader valve on the fuel rail--not much liquid comes out of there.

Back when I was running my +40 injectors and stock calibration, I had to turn my fuel pressure way down to like 28 PSI static or something like that in order to keep the air/fuel ratios leaner than 10.0:1. It gets better--I also had a check valve on the fuel pressure regulator's vacuum line so that no boost pressure ever got to the regulator, and it still ran rich as hell. I'm using a well-ported big valve head as well. Those injectors flow quite a bit more than stock!

So that means I was close to being in the same boat you guys are in. To help alleviate the issue, I switched back to stock fuel injectors and fuel pressure. I still get the problem, but its not as bad. A person almost wants a turbo timer to run their fuel pump.

When shutting the engine off, the fuel pressure should increase up to the static fuel pressure due to the fuel rail heat soaking. If you can rig up a vacuum solenoid to keep engine vacuum away from the fuel pressure regulator for the first several seconds of start-up, that will help keep things from boiling. It may not be boiling until the engine vacuum gets to the regulator in which the rail's pressure drops and results in instant boiling due to the lower pressure. Making the startup enrichment more aggressive on hot starts can also make things happier. That would be in the engine computer's calibration.

My 3100 powered Grand Prix had no hot-start issues. My V-6 Daytona has no such issues either.

[Keith-IR]

You could have a problem with the injectors (leaking under pressure). You may want to think about having them flow tested. Injector-Rehab - Fuel injector cleaning, flow testing, and complete blueprinting service.
Switching them out with the old ones may not have solved the problem if one of those older ones were doing the same thing (leaking).

[glhs496]

Thanks for all the good info.I do have some brand new +40's I could put in.
Since a computer swap causes the car to start immediatly I think that rules out the injectors, but I'm really not ruling out anything.

FYI My car made safe max power at 43 psi on this cal, the higher the pressure the lower the power.

I'll get that number and call Cindy too. Thanks.

[Reaper1]

I too think there's something in the fuel causing this issue. When I first got my cal I never had this issue. Once the car started from being dead cold, it would start EVERY time afterwards. Once the ethanol started being introduced to the fuels I started having this issue more predominantly. I DO know that a richer start situation in the cal would solve the issue though...

Another idea another person had was to have a manual switch to turn the fuel pump on. I thought about that too, but I do't want to have to worry about turning a pump on every time I go to drive the car, much less accidentally turning it off in the middle of a high boost run or something stupid like that....

[phantomrt]

You can easily rig up a manual switch to ground the coil of the fuel pump relay. That way, the engine computer will be able to provide the ground even if you forget to hit the switch or accidentally bump it or whatnot. Thats how I have my radiator fan switch set up.

Such an idea would work great, but I've sorta tried it with no good luck. I would just bypass the relay with a paper clip to run the pump a good minute before trying to hot start the car and it made minimal to no difference. I blame this on the fact that fuel does not flow through the rail, as in from one side to the other. It just kinda goes in one end and back out the same end, thus not purging the big air pocket in the fuel rail.But I think the only hope of this to actually work is to circulate the fuel for a few minutes at least after engine shutdown--hopefully that'll keep the fuel rail cool enough. Or, design a fuel rail that actually is a flow-through design. Maybe they exist already? Some have what appears to be a tube inside running the length of the rail. The ones I am using are just hollow. I even tried the stainless steel FFV fuel rail in hopes that it dissipates heat better. That didn't work either.