89 3.0 engine hard starting when warm

[19k40rocky]

My caravan use to stall out when I would come up to the stop sign. I ended up changing the fuel filter, and the oxygen sensor since it had a lean code. That really didn't change anything. I ended up changing out the IAC solenoid after studying the website and the haynes manual, even though it had not thrown anymore codes. It did help the problem with the stalling though! Problem now is it starts good when cold but don't want to start when warmed up. I have to press on the gas pedal about half way down to get it to start. Then it acts kind of flooded. If I rev it up 3-4 times and clean it out, before I put it in gear, it runs fine until the next time you shut it off and try to start it. I pulled the IAC out to make sure the adjustment was correct and was ok. I checked the vaccum hoses and can't find anything loose. The injectors were replaced when I rebuilt the motor a 100,000 miles ago. I am to the point I could almost give up live with it, but my wife sees it differently. Any ideas that anyone could give me on what might be wrong or what I am missing would be much appreciated! Thanks!

[rustysurfsa]

Your cars getting old man, as it gets older your need for higher octane gases is nessesary. Try 91 and see if you still have that problem. My mustang has a hard time starting when warm if i have regular. Your fuel might be preigniting. If not whens the last time you changed you plugs. It's about time.

[19k40rocky]

Thanks for the reply. I understand the getting old part. I had changed the plugs few months ago. I am wondering about the fuel pressure regulator. I got a gauge but cannot find the service port for the life of me. Any idea where it is?

[RIP]

According to this you have to disconnect the fuel line: http://www.autozone.com/shopping/rep...00c152800663a6

[19k40rocky]

Thanks for the info RIP! Probably going to be a couple days before I get the chance to put a gauge on it but I will let you all know what I found out. Thanks again!

[19k40rocky]

Well I did the check with a fuel pressure gauge and I am still perplexed. I hooked it up and turned the key to on and it pressured up to 44 psi but it would not hold the pressure. I tried it a couple more times and the same thing. I pinched the return line hose and it made no difference and kept dropping at a steady rate once it pressured up. I ended up starting it to see what it would do and seemed to start ok without having to step on the throttle but stumbled alittle bit at first. I did check take the vacuum hose off the pressure regulator and it jumped up to 54 psi and then back down to 44 when you put the hose back on. After I shut it off, the pressure held and it started fine. I let it warm up to operating temperature and let the cooling fan cycle once and then shut it off and pressure held again for the most part for a good hour but dropped only to about 30 psi in that amount of time. I tryed starting it and it started ok. I shut it off and left it alone for about 3 hours and saw the pressure dropped to around 10 psi and then it did not want to start. Got the idea to shut the key off and on 3 times to active the fuel pump and try to get it to pressure up good and this seemed to help with not having to step on the gas to get it to start like I had been doing. I had been thinking the problem was it was getting too much gas, now with what I did today I am thinking it is just not keeping good pressure when trying to start it at times. Any ideas what is going on here? Is there a check valve some place?

[RIP]

Maybe something here: http://www.knizefamily.net/minimopar/fuelsystem.html

Or here: http://www.autozone.com/shopping/rep...00c152800663a1 Select your type fuel system on the right column.

[19k40rocky]

Well I got a used fuel pump and tried that and it seemed to work and hold pressure. Thought I had the problem solved until came back home from test driving/running some errands and it acted up again. Got to looking at it the next evening and found gas in the fuel pressure regulator vaccum hose and coming out of the plenium and MAP sensor hose when looked further and pulled it off. Got a used fuel rail assembly on Saturday and put it on today. So far seems to be ok but tommorrow is another day! Thanks for all your help and ideas!

[Roadtrip]

I'll bet that the problem is a bad fuel pressure regulator. It's leaking past the diaphram and raw fuel is being sucked into the intake, especially when there's a high vacuum (like when coasting/engine-braking to a stop). Rough too-rich-like idle. Hard to start . . . take several seconds of cranking and some push on the pedal to get it to fire, whereas before one turn of the starter and no pedal produced an instant start.

It would also explain the leak-down and the fact that the computer is throwing no codes.

Turn the engine off, then disconnect the vacuum line to the pressure regulator and turn the key on. The fuel pump should come on momentarily until it builds up pressure. At the same time I'll bet there will be a geyser of fuel squirt out of the vacuum connection on the pressure regulator.

A new fuel pressure regulator is about $60, and you have to remove the fuel rail to install it.