Hard starting


dingobait
12-09-2014, 08:41 PM
1999 Rodeo LS 3.2L V6 M/T 287K miles

It has been starting "harder" a few times per day over the last week.
Sometimes it starts right up normally, quick crank and no gas. Other times it requires much more cranking and then a few taps of the pedal to start.

It seems to be happening more frequently over the past few days but it will always start.

I replaced the fuel pressure regulator and the fuel filter (external) along with the air filter, and that seemed to do it the first day, but then the occasional hard starting returned.

I also swapped positions of the fuel pressure relay and the heater relay just to see if maybe the pump relay was sticking intermittently, which I didn't think was happening since I can hear the fuel pump running when I turn the key before cranking the engine.

No hesitation while driving/accelerating, runs fine once started. Starts hard at different times during the day.

I'm planning to change the spark plugs this coming weekend just because they're due, but I don't expect that to cure this since it runs great once started and I have no CEL.

Ideas anyone?

Thanks,

Mark

amigo-2k
12-09-2014, 10:54 PM
The first thing that comes to mind is the fuel pressure regulator, but you already swapped that out ... the other classic reason is the intake manifold gasket is on the way out ... but if it was so bad that it had issues starting it should have issues at idle too ...

another thing to check is the EGR tube that exits right behind the throttle body, that the opening on the tube isn't plugged with carbon ...

Maybe dump in a bottle of that HEET stuff if there is water in the gas?

dingobait
12-10-2014, 10:49 AM
I'll check the EGR tube for certain and see what I can see, and I'll try the HEET as well just to see if I got some bad gas. You never know.

I really appreciate the input.

I believe there's also an intake screen on the pump inside the fuel tank? Seems it would cause some hesitation though? It's tough to figure since it drives fine.

The fuel pump and the electronic ignition keep running through my mind, but they're fine while driving, and the issue is intermittent but persistent.

Idle is fine, and no CEL's so I don't think the IMG's are bad.

This morning I had to crank it quite a bit. I'll see how it is the rest of the day. I have the feeling that one day soon it may not start. That may be easier to pinpoint.

I really appreciate all input. Thanks a million. I'll report back on whatever I find.

Mark

dingobait
12-10-2014, 02:06 PM
If I start it again right after turning it off, it always starts right away (so far).

Then again sometimes it starts right up after sitting even overnight.

I checked to see if there were any pending OBDII codes, but there are none.

I just put in a bottle of HEET water remover/fuel injector cleaner and filled the tank again.

We shall see.

Could be just wishful thinking, but it's worth a shot and cheap and easy, and it could be some injector mis-spray maybe???

I'm in Southern California so it's pretty dry, but you never know what can get into the underground tanks at the gas station, and it did rain very heavily recently after a very long time of no rain, so.........

I considered buying a fuel pressure gauge to read the fuel rail pressure with, but it seems to me that if it was a fuel pressure issue I'd feel it while driving?

One step at a time I guess. I'll check the EGR soon when I'm not at work.

dingobait
12-10-2014, 09:10 PM
This may not apply to my situation since the issue is intermittent, but should the fuel rail stay pressurized after the car is turned off?

If so, should it hold that pressure indefinitely? It's a sealed system isn't it?

Just wondering if I'll need to check that.

amigo-2k
12-10-2014, 11:45 PM
I agree that you should check the fuel pressure ... it still sounds like a bad fuel pressure regulator...

dingobait
12-13-2014, 05:56 PM
Yeah it does.

I'm going to install new spark plugs, mostly because they're due.

It's still very intermittent, but often. Sometimes after sitting overnight it'll start right up with a few cranks and no gas (normal), and on other days I have to crank it hard in the morning. Throughout the day there's just no telling.

It could be a leaky injector, or a leak in what I think is called the "return" line tube inside the tank. If the fuel pressure leaks out, then I believe it could cause hard starting.

Seems to me that if the pressure was leaking though, it would start hard every time, especially after sitting all night. It's the intermittent part that's puzzling.

I thought of replacing all of the injectors since they're all 15 years old, but they appear to be around $85 each, so I'll do the plugs and check all wires and boots carefully just to see.

So far: not the fuel-pressure regulator; not the fuel filter; not water in the fuel.

Next: spark plugs and fuel injector cleaner.

dingobait
12-15-2014, 02:05 PM
Well check this out.

It appears so far, after 11 consecutive strong starts, that it was the spark plugs.

They have 58,000 miles on them. I usually change them out at 50,000 mile intervals even though they should supposedly last up to 100,000 miles.

The color on all 6 is good, nice and tan, which is amazing in itself at 287,000 total miles on the vehicle, but it appears that the tiny platinum electrodes are pretty much gone on all of them.

AND, when zooming the pics of the plugs you can see lots of tiny crystal/ceramic looking deposits all over the tips and electrode which I've heard affects the spark quality/strength.

I tried to attach a pic, but couldn't. Both pic buttons seem to want to point to a link/URL only. This forum would likely get too weighed down with attached pics otherwise.

The plugs I removed were Autolite AP3924 which I just replaced with NGK BKR5EGP.

I'll of course be monitoring it, but for now this sure seems to have fixed it.

I'll report back in about a week if all stays good.

Mark
HB, Ca.

dingobait
12-15-2014, 11:53 PM
I spoke too soon.

After 11 starts, starts 12, 13, and 14 required a bit of cranking again along with some pedal tapping for a little gas.

Then I stopped and got gas, and it started up fine after that. Then I parked it at home and it started up again just fine.

We'll see how it does in the morning after sitting all night. Previously some mornings required cranking, and some didn't, which is why it doesn't "seem" like a fuel-pressure issue, at least not a consistent one.

I did move all of the coils and their associated wiring slightly when changing the plugs, and then I had 11 consistently strong starts before it started needing more cranking.

Could be a wiring issue, but it sure doesn't seem that way.

It has me wondering if one of the injectors is leaking pressure intermittently. That could be tough to nail down. I added a bottle of STP fuel injector cleaner just now when I filled up. Wishful thinking.

At least it always starts (so far), so I'm not "that" worried about it, and I will find the cause eventually. Worst case I'll have to call AAA to get me home at some point.

If it persists I may end up getting a fuel pressure gauge to further diagnose it.

dingobait
12-16-2014, 12:54 PM
After sitting all night, this morning it started strong, so it really doesn't seem to be a fuel pressure leak unless it's an intermittent one, perhaps an injector that sometimes leaks, sometimes doesn't?

I have a new theory I'm trying out. I'll report back more when I know more.

dingobait
12-18-2014, 04:44 PM
So far: Not the fuel pump relay, fuel pressure regulator, fuel filter, air filter, spark plugs, or water in the gas.

It's still very intermittent.

One day it'll start right up in the morning after sitting all night, but then start hard when I leave work for lunch, and the next day it'll start hard first thing in the morning and then start right up when I leave for lunch.

Could it be an injector that only leaks some of the time? Anyone seen that?

amigo-2k
12-18-2014, 06:08 PM
have you checked for an intake manifold gasket leak?

dingobait
12-21-2014, 06:02 PM
I haven't. I've been pointed to IMG leaks many times over the years but it's never been that yet.

I guess it wouldn't hurt to check those, but it sure seems to me it would likely run and drive a lot rougher, noticeably at idle.

It's so intermittent that it could be attributed to that possibly. The only other thought I've had lately is that it's losing fuel pressure due to maybe an injector that gets stuck open sometimes, but I really haven't checked into that thoroughly enough yet to know if that's even a reasonable assumption. I'm not fully versed in how much pressure the system should hold (if any) etc.

Anyone well versed in that? I have the manual so I will be relatively soon. Right now it always starts and life is very busy so this is an ongoing investigation.

Thanks for the tip though. I'll have to check it out if only to eliminate another possibility.

dingobait
12-29-2014, 09:33 PM
This issue is apparently fuel-pressure related.

The fuel pump runs for 2 seconds once the key is turned to the on position (the position before cranking) which primes every cylinder with a short burst of fuel, and then the computer figures out which cylinder is likely to fire first based on the crankshaft position sensor and other inputs/calculations.

In my case, if I wait the 2 seconds until the pump turns off before I crank the engine, it starts normally every time.

That leads me to reason that I could possibly have a fuel injector that's letting the pressure bleed off, or there could be a leak in the return line that's part of the pump assembly in the fuel tank.

I saw some pics of a fuel pump with a return line that had been torn during installation causing the fuel pressure to drop to zero immediately after the engine was turned off. The pressure shouldn't drop that much.

I read up on how to check for a leaky injector which involves removing the fuel rail with all of the injectors still attached, and then jumping the fuel pump relay for a few seconds before cutting it off so you can see if any of the injectors leaks fuel.

I've considered buying a fuel-pressure gauge so I can see just how much pressure is bleeding off, but I'm not sure that would lead me to which component it might be. Injectors are $85 each (x6), and the fuel pump is around $400, so it's a gamble to just replace either.

I may take a look at that soon, but for now this really isn't a problem.

I wait the 2 seconds until the pump stops (feels more like 3-4 secs), at which time I also hear what sounds like a relay click once (fuel pump relay?) and then I crank it and it starts right up every time and runs great.

I can always wait the 2 seconds.

It hasn't adversely affected my gas mileage, I have no CEL, and I also got CA smog-checked 2 days ago and passed with flying colors even at 287K miles with all of my original equipment including both catalytic converters. Pretty cool.

If the return line on the pump is leaking a tiny bit and this is the only issue it causes, then that's really not problem since it's not like the fuel is leaking onto the ground.

I'm still going to keep inspecting lines and watching for anything unusual, but at the moment this isn't something that needs to be torn into in my opinion.

Sometime soon I'm going to see if this issue is still intermittent like it was before I started starting it this way every time. If it's still intermittent, then it appears the pressure bleed off is likely small.

Any input welcomed. I'm going to live with this for a while unless it disappears on it's own.

Mark

amigo-2k
12-30-2014, 05:03 PM
I've been doing that start-up technique for about 10 years ... turn the key, put on my seat belt ... adjust the radio then start it up.

If I didn't it would sometime take longer to start ....

dingobait
01-10-2015, 07:04 PM
Yep. That's my start-up technique as well now Ryan, and as you know it's totally a non-issue.

It's strange that it's intermittent, that's for sure, but since it always starts with that technique, runs fine, and even passes smog easily, there's no need to dig further.

I really appreciate your input as always Ryan. Thanks a million. I really like being able to document issues on this forum in the hopes that it can save others grief and $$$.

For now, onward.

Mark
HB, Ca.

dingobait
02-14-2015, 03:11 PM
Still using this same start technique.

Make sure the radio is turned all the way down.
Turn the key to on (just before cranking).
Listen for the relay click (3-4 seconds).
Crank it.

Starts right up every time. No issue. Gas mileage same as always. No CEL. Passed smog easily.

It's a non-issue. Over and out on this one.

Mark
HB, Ca.

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