Runs Awesome! But won't start first try

[sethhatfield]

Well bad news. I thought my intermittent no start was fixed but nope. I started having the same problem again so I changed the fuel pump today. No fix. I'm beginning to think it is an ignition problem.

Any thoughts guys?

[upallnight]

I would check the vacuum hose that attaches to the Fuel Regulator. You could have a vacuum leak.

If you can attach a fuel pressure gauge to the fuel rail to determine what type of fuel pressure you have when the engine is trying to start. Also keep the gauge attach to the fuel rail and see if it can maintain the pressure. You might have a leaky injector.

You need to do some investigative work instead of throwing parts at it.

[jbny]

Sethhatfield - I have had something similar with my 4.8is, though I never had to try 5 times , more like 3-4 times max and then the engine fired.

a. Couple of years back on my trip to Maine i suspect bad fuel quality caused this issue , did not repeat for 8 months ..once i came back to CT.
b. After 8 months from the first instance it started happenning again, and my battery died too, I ended up changing the battery to AGM type and have never had any issue since.

I did not try to diagnose this issue so just off my personal experience, hope this helps.

[sethhatfield]

You know...that's very helpful! I think a weak battery can cause all kinds of problems. Seems like my problem went away for quite awhile after I changed the battery over a year ago. A little extra voltage makes all the relays perform more consistently. It is hot as hell here in Houston 99 degrees this time of year and that drags on the battery.

I threw a fuel pump at it because it made sense and it was only $78. Obviously I didn't buy the whole assembly for $364. An extra 15 minutes of simple modification is all it takes to install a universal higher flow unit.

I'll check the vacuum line to the fuel pressure regulator but that actually reduces fuel pressure at idle so I don't think it would cause this particular issue. I already replaced the fuel filter/regulator just because it was cheap and had never been changed.

[upallnight]

Originally Posted by sethhatfield

You know...that's very helpful! I think a weak battery can cause all kinds of problems. Seems like my problem went away for quite awhile after I changed the battery over a year ago. A little extra voltage makes all the relays perform more consistently. It is hot as hell here in Houston 99 degrees this time of year and that drags on the battery.

I threw a fuel pump at it because it made sense and it was only $78. Obviously I didn't buy the whole assembly for $364. An extra 15 minutes of simple modification is all it takes to install a universal higher flow unit.

I'll check the vacuum line to the fuel pressure regulator but that actually reduces fuel pressure at idle so I don't think it would cause this particular issue. I already replaced the fuel filter/regulator just because it was cheap and had never been changed.

If the line hold vacuum it will reduce the pressure at idle, but if you have a leak it will be like WOT so it will increase the pressure in the fuel rail.

[Dudewanarace]

This may sound odd, but when I had a cam position sensor failing, I would get the start problem you describe. I couldn't reproduce it each time, it was random. Not long after the problem started, I got a code for one of the cam position sensors. Thinking it was just a different problem, I replaced the cam position sensor. Well, it has never failed to start first try again. That was years ago..

[sethhatfield]

Thanks. I haven't ever gotten a code unfortunately.

I swapped the fuel pump relay for one in the back as they are the same, no fix.

I'll try a couple of cam sensors. I can change those pretty quickly and they are original. When I changed the timing chain guides they were pretty ugly and caked with crap they I had to clean off.

I've got another fuel pressure gauge coming so I can leave it on there and see if I can duplicate the problem while it is installed.

[jgold47]

I think the fuel pump thing you did may be the problem. There are a series of check valves in the stock style pump to hold pressure.

[sethhatfield]

Yeah that can't be the problem since I did that after the problem started. The pumps are the same with the same check valve.

I've ordered a couple of cam sensors because their magnets do weaken over time and these are 13 years old.

It just did it to me tonight until I tapped on the fuel pump relay and then it started right up! Could be a coincidence but I'm buying a new relay too, they're cheap.

Thanks for the ideas.

[alecu]

I had a similar symptom and it was a leaky injector. Remove your injectors and put a paper towel underneath. See if any leak that way. I was loosing pressure after the engine was turned off.