NEWB!! Rough Idle, won't take gas, once gas comes up...

[CoryBrown50]

Hello All,
I hope that the great and powerful brain trust can help me out with this one.....

Here is what I have,
1998 Ford Expy with the 4.6 motor
I bought it with the PO stating it needed new cats....not running.

Here is what I have done....
CAT GUT with 2nd O2 sensors on plug foulers.
New fuel filter
New PCV
New Air filter

So now the motor starts, and runs, but only at about 500 rpm, and will not take any gas for a while. After holding down the gas pedal, for about 1-2 minutes, I can get the RPMs up, and motor runs smooth. No CEL on the dash, which does work when the key is turned to check the lights.

So, to state my obvious question.....What is wrong? Where should I look to next?
I could state all kinds of ideas, but would rather hear from anyone with a new set of eyes.

Thank you all....

 

[Bowesmobile]

First check fuel pressure. Should be around 40 psi. If not, its the fuel pump or regulator. Next make sure all electrical connections are made. Then run codes in the computer. Then check spark plugs and coils. Stop at the one of these that fixes the problem.

 

[Exia]

You could have a bad TPS, or a fuel injector issue, I would go ahead and run a DTC check even if the light is not on you could still be throwing a code... My light would flash and kick off when I had a DPFE, O2, & misfire code. So start with the SES first.

 

[bricekin]

If the check engine light isn't coming on with the ignition switch on and the motor not running then the bulb is burnt out or someone yanked it.

Get the DTC codes read.

Unplug the mass air flow sensor and see if the condition changes. Unplug the throttle position sensor and see if the condition changes.

Report back.

 

[CoryBrown50]

Check engine light works, just not illuminated. I went to Autozone to get the fuel pressure tool on rental. I will check the fuel pressure tonight. Also will check the MAF and TPS suggestions. The MAF is clean, but it could not be working.

On a semi-side note....I pledge that whatever the answer ends up being, I will post the resolution. There is so much wonderful info on this forum, but too many without final solution statements.

Again to the brain trust.....all help is greatly appreciated!!!!!

 

[CoryBrown50]

Ok, went tonight and got the fuel pressure gauge to hook up to the line. As long as I hooked it up correct, the highest reading was 10psi, but mainly at 0.

Checked the fuse to see if that was popped, hoping for a cheap fix, with no luck there.

Pulled the MAF sensor and no difference.
Pulled the TPS and no difference.
Put starter fluid in past the MAF sensor and the engine idled normal with the additional fuel.

Are we all thinking the fuel pump? Is there anything else I should look at before shelling our $250 bucks? Any tricks to dropping the tank or replacing the pump?

Thanks again for your help.....

 

[semperfi96]

fuel pump it will be, that sux I know but thats the same issue I had and what allowed me to buy my truck so cheap, 1 owner didnt wanna fix and bought a 3rd edition.

 

[CoryBrown50]

The price was definitely right....$900.... I wish I would have checked that all out though before ripping the whole exhaust system off..

There are a lot of junk yard fuel pumps out there on the cheap....any thoughts about them versus the Autozone ones?

Thank you all....

 

[semperfi96]

go new, you never know what your going to get with electrical parts in bone yards. Plus you'll have a warranty

 

[robbieg]

Do not get an airtex fuel pump, go with the OEM Bosch

 

[Exia]

Since I dont know what 4.6 you have ( OHV, or SOHC ) I looked both up

1998 FORD EXPLORER Fuel Pump 4.6 SOHC

1998 FORD EXPLORER Fuel Pump 4.6 OHV

You can buy rebuild kits for 30 bucks, or buy a new one for 70 bucks

 

[CoryBrown50]

So.....
Replaced the fuel pump. That was the hardest easy fix I've done in a while....at least the bolts didn't break to hold the tank up..Also had a motorcycle lift to hold up the tank, much more stable than a regular lift. It looked original.

Just to make sure, I thought there was only 1 4.6 in 98, the SOHC, but to confirm, my VIN has W4W in the middle.

Anyway, not sure what the fuel pressure is now, as I gave the tool back to pay for the pump, but the engine will now take gas. In the beginning of revving the motor, it is sluggish, but once the revs go up above 1000, the gas response is instant, but before was not. If I feather the gas, I can keep the revs up and everything sounds fine. The problem is the idle and in gear.

At idle at start, it is still low, 3-400RPM. If I rev the motor up and get it warmed up, I get the idles to stay at 750 or so without any pedal input from me. It runs smoothish at that level.

If I put it in gear and try to give it gas, it will not take it and will shut down.

As before, I have my thoughts, but appreciate the input of others.

Thanks again.

 

[Exia]

So.....
Replaced the fuel pump. That was the hardest easy fix I've done in a while....at least the bolts didn't break to hold the tank up..Also had a motorcycle lift to hold up the tank, much more stable than a regular lift. It looked original.

Just to make sure, I thought there was only 1 4.6 in 98, the SOHC, but to confirm, my VIN has W4W in the middle.

Anyway, not sure what the fuel pressure is now, as I gave the tool back to pay for the pump, but the engine will now take gas. In the beginning of revving the motor, it is sluggish, but once the revs go up above 1000, the gas response is instant, but before was not. If I feather the gas, I can keep the revs up and everything sounds fine. The problem is the idle and in gear.

At idle at start, it is still low, 3-400RPM. If I rev the motor up and get it warmed up, I get the idles to stay at 750 or so without any pedal input from me. It runs smoothish at that level.

If I put it in gear and try to give it gas, it will not take it and will shut down.

As before, I have my thoughts, but appreciate the input of others.

Thanks again.

It sounds like some serious issues, get a code reader and check the ECU for current or previous codes before you start trying to buy tons more parts.. Or you may start seeing more cash leaving you're account and nothing to show for it

 

[CoryBrown50]

Thanks Exia,
I went and got a code reader this evening.
No codes stored.....


Right now the only thing I can think of is maybe the inside of the muffler collapsed and there is not enough flow. It feels like normal flow through, but what do I know.

When I started it, it ran at about 300-400 RPM. After about 30-45 seconds it stayed consistently at 500-600RPM. Still takes a minute to take gas, but again, once it is getting gas, it is consistently responsive.

Other idea was maybe the idle air control module.....

I sure hope this thing can get working. My daughter asked me tonight why I replaced our broken truck with another broken truck.......The truth spoken by a 4 year old....

 

[Bowesmobile]

Hmm, thats an interesting problem. No codes and it still runs rough at initial start up? Did you replace the fuel filter as well? Also can you drive it at all to see how it responds under load?

I understand getting some truth from your young ones. Mine have done that to me as well.

 

[Exia]

Thanks Exia,
I went and got a code reader this evening.
No codes stored.....


Right now the only thing I can think of is maybe the inside of the muffler collapsed and there is not enough flow. It feels like normal flow through, but what do I know.

When I started it, it ran at about 300-400 RPM. After about 30-45 seconds it stayed consistently at 500-600RPM. Still takes a minute to take gas, but again, once it is getting gas, it is consistently responsive.

Other idea was maybe the idle air control module.....

I sure hope this thing can get working. My daughter asked me tonight why I replaced our broken truck with another broken truck.......The truth spoken by a 4 year old....

That is extremely weird..

Ok normal idle on that should be 600 to 650 ( I am using mine as a template ) try and start it, get it running walking out and put you're hand over the exhaust, see how much pressure is coming out..

Get a tester to test the fuel system, just to see how much you have going through the system, it could be the filter is clogged. I would say could be a injector issue, but since you are not throwing and codes that kinda eliminates that.

Try those two things and let us know..

 

[CoryBrown50]

Thank you again,

In feeling for the exhaust, how much pressure should I be feeling for?

 

[Exia]

Thank you again,

In feeling for the exhaust, how much pressure should I be feeling for?

Should be a constant pressure.. If its pushing your hand away, or if it takes some effort to keep your hand near the outlet, you have descent exhaust, but if you can basicly cup the pipe with your hand with little resistance, exhaust could be, becoming clogged.. And again since you have no codes throwing, I am going to be reluctant to say the cats are bad..

Also I have been thinking, go and grab a bottle of HEET for the fuel, you may have water in the gas, if you see a difference, after that, than change filter and drain the fuel

 

[semperfi96]

could have some cat problems too.

 

[CoryBrown50]

Ok, got in tonight and no real pressure from exhaust out.... just the lub lub with the engine. I could easily keep my hand there.

I was thinking that the gas may be bad as well. No telling when the PO last filled up. I'll get the HEET tonight and in her for tomorrow. When you say replace the filter do you mean again? It is a brand new one.


I was going to unhook the muffler (my neighbors' hate me anyway) and see it that is where the blockage may be. I'm not sure is I'll get to it tomorrow with the weather, ISAAC is supposed to show up here tonight or tomorrow.

Thank you as always, all help is greatly appreciated by myself, my wife, and my overly honest 4 year old.