305 tbi starts , immediately stalls, runs good on 2nd start?

[95Noobie]

Brand new wrinkle today. Drove 15 miles this afternoon ran great. Parked 30 min. Hit starter and started quickly like normal but ran 2 3 seconds and abruptly quit. 2nd start starts normally idles normally and runs normally. Ran 20 miles, turned off 15 min. Hit starter and same quick start and abrupt kill. 2nd try normal and idled fine

Can't think of any other changes. Last tank of gas I put 2 cans of Techron cleaner through. That tank is gone and I filled up yesterday but it ran well this am and problem new this aft.

Ideas? It acts as if fuel line is draining back in the tank or leaking so gas in throttle body runs out and new supply needed.

Does the fuel pump run in the accessory ignition position like on my newer suburban? Maybe I need to change startup procedure?

I hope pump isn't getting weak?

I can't find a leak and no puddles on the ground. Perhaps leak is on top of the tank or a fitting?

 

[docstoy]

First question what is fuel pressure with pump running, have you always run 2 cans of cleaner as maintenance of fuel system ? My next thought would be when was last time fuel filter was changed ? And my last would be fuel pressure regulator and of course what year, powetrain ?

 

[95Noobie]

1995 silverado 305 4l60e 4x4

New fuel filter a month ago.

I learned here I can't check fuel pressure without taking a line apart and install a T and gauge which I don't have.

It was suggested here to try techron before getting injectors cleaned or new injectors as a general tune up suggestion as part of our desire to explain 305 with low power. The conclusion was if it runs well it might be normal for 305 to feel doggy because it is doggy.

The past discussion was before the new symptom today.

Is the symptom only at first start helpful in narrowing what happens after a time of rest that removes available gas in the lines?

 

[docstoy]

So you have a tbi and not a vortex ? By using cleaner may have restricted fuel filter and have seen it affect regulators. My thought on 305 is yes it doesn't have as much hp but is enough for some , I had a 305 in a '91 ext.cab and I thought it was fine, wife totalled '91 so now we have '94 350 extended cab

 

[95Noobie]

Yes, TBI and the fuel filter is new, but I know when we cut the old one out (cut it out due to corrosion so bad on the fittings) that pretty nasty rusty sludge came out of the old one. I have no idea condition of the inside of the tank or the age of the current fuel pump and sender. Judging by the rusty bolts and straps it has been in there a while.

I don't understand how a fuel line cleaner would add restriction but if that is the case it would be very simple now to replace the fuel filter again since I have repaired metal lines on both side of the filter (where someone had used rubber hoses to patch it in) and the fittings on the current fuel filter are brand new so easily removed.

I dropped off the truck tonight (much longer story) to get the transmission rebuilt. We were getting slow activation into reverse and slipping if trying to back up a slight grade. We were occasionally getting a hard shift between one/two but only if steady pressure on accelerator was holding rpms up before the shift. I debated finding a rebuilt one and putting it in but research showed that this transmission was unique in its attachment to the transfer case in the 1995 year and would be very hard to find that exact setup in a rebuild shop.

While it is on the hoist they will check transfer case, seals, and look for any unusual findings. I asked while the tranny was out to drop the oil pan and put a new gasket in since I think the slow drip off the bell housing of oil was coming from the leaking oil pan gasket.

Of course none of this relates to the new issue with the engine not appearing to pump enough fuel right at startup to keep running on the first try.

One other variable but hopefully it is not related, there are posts on this forum where a hard 1-2 shift was related to low power on one of the wires going to the ECM. The video shows very clearly the problem with the low voltage giving a higher than normal pressure build up and a hard 1-2 shift. I did swap my ECM computer and PROM using an exact match from a donor 1995 chevy. The truck ran normally after this switch for about 2 weeks so not sure that could still relate. I guess I could easily swap back to the original ECM or at least swap the PROM back as a troubleshooting step.

This project has been way more expensive and time consuming then every imagined. We have faced nearly every hurdle mentioned in this forum.

Assuming the rebuilt transmission will be solid for a long time and it goes well, I was toying with LS swap but the price tag is insane. Swapping a 350 TBI probably won't give much of a difference. I think we may just have to stick with the 305 for now and try to idealize its performance. The tranny shop guy has some history of doing a few LS swaps and he said before we go through the time and cost for limited improvements in power, (it is a 5.3L vs 5.0L displacement), he said our budget could more easily handle the simpler task of putting a slightly 'souped up' cam (he mentioned an RV cam). But that is only after we get the engine starting and running normally again.

 

[docstoy]

Is that your truck in the pic ? If so tires can't be helping , I assume you don't have a fuel pressure gauge ? What about the trans shop, is he a reliable source for other cks/diagnosis not wanting to get in your pocketbook , but fuel pressure is a important thing to know . What are you wanting your truck to be capable of ? Hope we aren't going over things you stated before . What was your previous thread title so I can read what was talked about .

 

[95Noobie]

Yes, that is the truck and I'm sure you are correct the heavy rims, wider tires and bigger offset taxes the motor pretty good. WE did sell those rims and now have lighter rims, still on a BF Goodrich KO2 305/55/20 (33") but on a narrow rim with no offset. It fits under the wheelwells again.

The engine always started normally after a brief crank and always idled well. Never seemed to have good acceleration or ability to pick up speed well even on the highway. That was when I researched as much as I could here and went through and checked things i could check. Along the way I found vacuum lines cracked or duct taped which I fixed. The old EGR was pretty stiff and corroded and replaced that. Along the way also replaced the coolant temp sensor by the thermostat, TPS and air sensor.. I have a obd1 scan tool but not one that can pull live data. (Grr.. I bought it as it was advertised that it could)

Prior to our getting it someone put in new plugs, wires and distributor. I observed the fuel spray prior to this event and it appeared symmetrical and strong but beyond that I haven't tested the fuel pressure. I guess if someone helps point out how to purchase or make an inline adapter and where or how to insert it plus the source for the fuel pressure gauge I'm willing to learn and do it.

I was talking to my son some more and the only other clue he can think of is that he was driving last weekend on a 2 lane highway that comes to a long descent into a river valley. He said on the way down the descent the engine did falter for a second and then was OK and he didn't know if gas sloshed to the front and the fuel pump ran out of fuel for a second. His tank should have had at least a 1/4 tank left at that time but maybe that is a clue as the engine never missed or stumbled before.

The transmission guy certainly has done all kinds of auto repairs in the past and I think he could help if I needed him to. I think we'll let him focus on the transmission rebuild and when he is done if it goes well i can ask him how hard it would be for him to get a fuel pressure gauge set up.

I'm curious if it is randomly time to worry about the fuel pump or if the techron truly is bad for a vehicle. I also can swap back to original ecm and prom but not sure we can expect a change there either.

 

[95Noobie]

Right now the first step is try to get back to feeling comfortable that it is running correctly. Then we decide if we want to put any more effort/money into boosting the performance. Not looking to roast the tires, just looking to be able to pull a light trailer at highway speeds without taxing engine. We did notice on the last tank the mpg was at 8 instead of 10 with normal around town driving and no towing so something may be amiss still.

 

[docstoy]

Nothing to do with start but I suspect your gear ratio is the reason for doggy feeling, along with tires being to tall. I'd think you should be able to tow, just tow in 3rd and not overdrive . 4l60E isn't a hard transmission to build its just the R&R that takes up your time . Guess when you get it back from trans. shop inspect fuel filter . By the way what is your gear ratio ?

 

[docstoy]

So your scan tool, you can't watch live data while engine running ? Reason for fuel filter ck after cleaner, it's kind of like taking a bath after you have been rolling around under your truck all day, water starts out clear but by the time your done it has a cloudy darker color, so if you had a lot of stuff in the one you replaced and then repaired the lines then there's a good chance the old filter wasn't taking all the contaminants out and by using cleaner ( which is good idea ) you may be loosening up stuff that has accumulated over the years and now it's in your fuel pressure regulator which now is getting a dose of cleaner which may be binding or restricting regulator and then thru engine and onto O2 sensor . A classic sign of regulator problem is start/stall restart is fine with no signs of performance difference . Have engine / body grounds been inspected /cleaned , on TBI clean grounds are crucial for good feedback to your ecm/pcm, again dirty grounds will lead to sluggish performance . Hope I'm not just boring you with long post, just trying to help