1996 VP 5.0fi ford surges at idle, missing timing marks?

[Justin Kennedy]

I've just finished repl. longblock on my motor. It runs great except for idle it surges between 800-1200 rpm. Once in gear, its fine. Also, I am unsure about the ignition timing because there does not appear to be any marks on the block. Could the timing be the cause of the idle surge? I have checked the vacuum lines, replaced the tps sensor, cleaned the throttle body, repl all gaskets, checked for air leaks in fuel lines(didn't find one yet)cleaned entire fuel system. filled w/ new gas. JK

 

[Don S]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

I don't have much experience with the Ford EFI, but if you go up to the Adults only sticky, and look in the Volvo section, you can download the OEM manuals for your engine. You will need the full model number, year of your boat doesn't work.

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

It's a 1996 NC model. Still can't figure out where timing marks are on balancer. VP manuals confirm "pointer" on block. I have that but i have no degree marks on balancer. Ive cleaned the balancer well and cant find even a scratch of a mark. I think the base timing is critical for proper idle. I can get it running fine just by rotating distributor. I sounds great but wont idle steady.

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

Hi, I have the same motor. I had the same problem. I thought it was the timing was out on mine and it ended up being the anti-siphon valve on the gas tank was bad. it was sticking and corroded. I also replaced all the fuel lines up to the fuel pump. if that does not work Look near the high pressure fuel pump there is a reservoir that the fuel goes into, there is a float inside with a needle valve there that could be set wrong or hanging up. I also added a racor fuel filter to the system to help catch any water the might be in the system.

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

Thanks. sanded(a lot)balancer and found marks. reset timing, it was off but did not help idle problem. will check anti siphon valve.

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

just thought of one more thing that could cause it too. if you have not done so just check the screen that is on the pick up tube in the tank, it might be full of sludge.

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

checked anti-siphon valve, checks good, replaced fuel line and inspected pick up filter, very clean.
Im going to replaced the idle air control valve. thats about the only thing left

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

one thing with the anti-siphon valve it will seem to work and fuel will get through but not enough. the other thing i changed Idle air controller it did help some, but it all went back to the anti-siphon valve. i figured for the few dollars for the valve i would change it. but let me know how you make out.

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

My anti siphon valve looks clean and appears to be working properly, check ball goes back and forth no problem. Was that the case w/ yours? I will definately replace it like you said, what have i got to lose? I put on a new IAC and it did help when the engine is cold, after warm up it surges again. I am also having an issue when i'm cruising, the engine stutters as if someone turned the key off then turned it back on. The problem will stop if I slow down for a few seconds, then I can resume cruise speed. Sound like an anti-siphon issue to you??? I'll give it a try tomorrow.

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

The same thing happened with the crusing. that is how I found the water in the tank. it would run good for a few minuted and then feel like someone shut the motor off then on again. sound like a good chance you have water in the tank. I also added a racor water filter before the volvo filter. to help get more of the dirt and water.
Mine was the anisiphone valve. the ball worked but it was too stiff for gas to go through. what had happen was the owner before me had water in the gas and it messed up the inside of the valve. since you got that far, i would also check the dip
tube that goes in the gas tank, ther might be sluge on the screen blocking fuel flow.
and while that is out try to get some of the gas from the lowest point of the gas tank.
see if there is water in there. if there is, either drian all the old gas out or do what i did
and just siphone the as much of the water out as you can. if this dont work i will try to think of anything eles i did during this time mine was doing the same as yours.

 

[dannyual767]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

I'm going to start this off by saying that I've got lots of frustrating experience with my 1991 Ford Mustang GT with the 5.0 engine. I'm not sure how much of it is like your boat but hopefully what I post below may at least point you in the right direction. In any case, I'd at least find somewhere to download the proper manuals for your engine.

Good luck!

Here is a partial list of the many things that can cause a rolling/surging idle on a Ford EFI 5.0 engine (car, i.e. 5.0 Mustang.)

IAC
- TPS
- PCV system
- Vacuum leaks
- MAF
- Oil dipstick bad seal (believe it or not)
- O2 sensors
- Salt & Pepper connectors problems
- Wiring issues
- ECM
- Aftermarket Parts not compatible/calibrated
- Thermactor system (I don't think you've got to worry about this on a boat.)
- EGR


I've fought the same problem with my 1991 5.0 Mustang GT. Very frustrating and difficult to solve. Vacuum leaks are a major problem and very, very difficult to find at times. If your 5.0 has the large intake manifold covering the top of the engine like mine does, it hides vacuum lines and vacuum trees. Very difficult to look at them to confirm whether or not a vacuum leak exists. A vacuum leak can come about from the lower intake manifold not sealing properly to the heads as well.

Here are a couple of links to a very large Mustang forum that should give you some information to get some more ideas.

http://http://forums.corral.net/forums/5-0-5-8-engine-tech/1160930-rolling-surging-idle.html

http://forums.corral.net/forums/5-0-5-8-engine-tech/746079-help-surging-idle.html

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

I replaced the anti siphon valve, still surges. I have read all about the mustang/f150 similar problems and im beginning to think this is the case. I just ordered a new low pressure fuel pump although I dont think it is the problem. I do know that my existing pump is 15 years old and while it seems fine to me, I've gone this far...why not. Haven't taken it to the water yet to check if anti siphon valve solved hi speed stutter. Ive got my fingers crossed. I read about an update kit from ford with an adjustment screw located in the spacer between IAC and throttle body, anyone used one of these with any success?

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

I wonder if the float level in the vapor separator is critical? I am going to check the manual on that.

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

there is a float in there you could check, I did rebuild mine and adjusted the float.
have you batteries load checked too at a auto parts store.found mine would not hold charge. that is the last thing i did was have that batteries load tested. but my problem was water in gas tank and the anti siphon valve. when the motor is running check the fuel pump see if it is hot if it is you are not getting enough fuel to the fuel pumps. my low pressure would get so hot that it would burn your hand. now that the fuel problem is fixed the pumps stay cool to warm. with this surging problem i went through a few fuel pumps before I found the problem. also when the surging problem was found the high speed hesitation went away.

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

Well no luck so far, even tried a new MAP sensor. I have done everything you and the others have suggested. I siphoned my tank out from the beginning and added 25 gal of fresh fuel. I have replaced the fuel filter twice and i didnt see any water the last time. I wonder if i need to take the tank out and really clean it out. My pumps do not get hot and sound normal, i have verified that they do pump gas well. I have 32-34psi fuel pressure at idle. I cleaned the vapor separator twice although it wasn't dirty at all, it looked brand new inside as well as the fuel that was in it on saturday when took it apart to check that the float wasnt stuck. I checked the float level in the manual, it shows its position as it actually is. My #1 battery is brand new and seems fine. I am not using #2. it is older and it doesnt hold a charge very long. I also have a brand new 65amp alternator. The volt meter on the dash shows strong 14volts. I think I'm going to really look into the tank/fuel for water. Thanks for the help.

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

only one more thing i can thing of at this point is to check the ground cables from the battery to the motor. they could be dirty. just a thought, did you try to run the boat of a different fuel source? like a gas can to see if that changes the way the motor runs. i would take the tank out as a last resort. but i guess it could not hurt.

 

[Justin Kennedy]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

So far no luck. tried idle air adjustment kit, no luck.

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

one last thing that i can think of would be the map sensor. see if you can get it tested.

 

[dannyual767]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

one last thing that i can think of would be the map sensor. see if you can get it tested.

In post #15 he said that he already tried a new MAP sensor.

 

[shdw2001h]

Re: 1996 VP 5.0fi ford surges at idle, missing timing marks?

how about vacuum leak.also might want to check the filter to the map sensor, could be clogged or very dirty. I went through everything i could think of.