Hard starting or not starting after the engine was shut down while it's hot.

[musicman76]

In a nutshell, 96 aerostar 4.0. Starts and runs fine until shut down, would start again imediately, but set for a few minuets and no start. Have to bleed off the fuel pressure from the rail to restart. it will build pressure back up to 15 lbs 2 or3 times before it will stay at 0 lbs. My mechanic says fuel pump,is this correct? Like the info on this site but haven't mastered how to use it, don't know if i will be able to. Not too much into sitting at a computer. !

 

[BrooklynBay]

What's your fuel pressure while it's running? Take a reading when it's cold then another reading while it's hot. Do you have a check engine light with a code? Do you hear the fuel pump prime when you have a no start condition? The title was updated to include more information.

 

[musicman76]

no start when hot

My pressure is 30 lbs. at all times, however, when I did a volume test only got about 6 oz. in 15 seconds. I just came home to get a tool and shut if off after about 15 miles of driving. 5 min had passed and it would not start. Got out my pressure gauge to relieve the mostly air pressure from the schrader valve. only about 2 oz. of fuel was expelled. Just went out to the truck and let out a little more air. Now it will start and I can get back to work. Where is all this air coming from? there is no pressure in the tank, air, that is, and that wouldn't be getting into the system. It does produce more air, fuel vapor?, the longer it has been driven, 40 miles yesterday and i bled off that air pressure 4 times before it stopped producing it. Then, no problem, starts right up and runs fine. Yes, i do have a code involving the #2 shift solenoid.but no others. Have replaced the coil pack,wires and plugs. Waterpump was leaking so we replaced it along with the thermostat. New brakes all around. My mobile mechanic really had fun with the drums but they stop me very well now. Sure miss my '97. Thanks for your time Brooklyn Bay P.S. Yes my pump is priming correctly with key on engine off

 

[BrooklynBay]

When was the last time you replaced the fuel filter? Check the fuel pressure regulator to see if the diaphragm is leaking by unplugging the vacuum line. There shouldn't be any gasoline in the vacuum line. Keep the fuel gauge connected to see if the pressure rises with the vacuum line disconnected.

 

[musicman76]

no start saga

The fuel filter was replaced a week ago at the advice of my boss. No difference. I believe I changed that out when I bought it 2 yrs ago. Forgot to mention that i also replaced the tps and act? sensors too. There was a good size hole and deteriorated gasket on the intake tube before the throttle body which also was repaired, thanks to my '97 parked in the driveway. Been robbing it to make this one whole again. Would take the drivetrain out of the '97 for the '96 but because of the 5 speed it seems too much trouble, 2 extra wires on the harness for the 5 speed. Will try out your suggestion in the morning before I go to work and report back tomorrow if possible. I'm thinking regulator myself but who knows at this point. Just trying to learn how these systems work. They sure can be a challenge. I love a good challenge. Your link on how these systems work is exellent. Something with fuel injection in it's link. Ok Brooklnybay, removed the vac line and was dry. At prime it went up to 30 lbs. on the first key on,, then up to 35 with each turn of the key, no higher.When started, vac was good and guage fluctuated between 30 and 40 lbs.Well, off to work, check for a reply when I get home this eve. Thanks

 

[BrooklynBay]

You mentioned that it was siphoning air into the lines. The sump inside of the gas tank might be what is causing the issue. It seems like once there is a prime it continues to draw gasoline. Does this happen once the tank goes down to 1/2 or 1/4 but starts correctly when it's full?

 

[musicman76]

new info

Good eve Brooklnbay, Just got home and decided to do another test. I took off the fuel tank gas cap and the engine died. did sound as if it had vacuum in the tank. It will not start now after 10 min. Now i'll go out and let the air out of the rail and my guess is it will start right up.....................too hot to get to right now. Is this sounding like a fuel pump problem to you? to answer your ? I don't believe it makes any difference if the tank is full or less rhan half but it might. Today it was 80 out and it seemed a little faster to build up that air pressure. Had to bleed alot off when I made a short trip to a locksmith, was in there 10 min and came out to a no start. I had my finger on that relief valve on the tester at least a min. and the amount of air that is being expelled is like gently blowing through a straw. Does that info help ? I guess any info I give you would help!

 

[BrooklynBay]

I'm still going to suspect that the sump is drawing air into the system after reading what was posted. A vacuum sound when removing the gas cap means that the pump is sucking in air instead of fuel. It's possible that the lower part of the sump might have a cracked hose. Filling the tank up to the top will completely submerge the damaged area with fuel. If you see that the issue starts around 1/2 or 1/4 tank, then run the tank down as low as possible without getting stuck without gas, remove the tank, and repair the broken line on the sump.

 

[musicman76]

ditto

I am leaning towards that myself. It did seem to be at its worst when under 1/2 tank. I presume this pick up or hose is between the gas and fuel pump. That would make sense. I was thinking if it's anywhere else, I would have low pressure, if at all. Plus I guess I would also be on fire. Have to laugh. Try to keep my tank full till mid week then finish out the week running it down for repair/replacement next week end. I'll post how it goes, if it don't crap out before then. Thanks, Dennis in houston

 

[BrooklynBay]

Aerostar fuel sending unit.

These diagrams came from my Ford software.

Check the areas which are circled for damage.

 

[musicman76]

tank switch

Good morning BrooklynBay, I also have that ford software, although it covers the 97 aero that I own. I have a question to ask. Can I drop the tank from the 97 and just switch it over to the 96?

 

[BrooklynBay]

It's possible to do, but why would you want to do that if the sending unit & pump are fine? Most likely it's just a piece of hose that has to be replaced. Are both of your tanks the same size?

 

[musicman76]

tank switch

well. ya gotta point there. I'll have to look at the procedure for dropping the tank. Probably the van i'm using first and take a look at the pump. Seeing how the pump is at the bottom I can't see how it could be sucking ais unless it's the pump itself that's cracked. Gues i'll find out.

 

[BrooklynBay]

The sending unit with the fuel pump are in the middle of the tank. A ripped or loose inlet filter sock or a broken hose connection will draw in air if the fuel is below the area with the opening. This is the reason why I mentioned that you should make sure that the tank is completely full of gasoline to see if it's still drawing air into the system. Removing the tank from the second van will just add to your labor.

 

[musicman76]

Fixed

Well, what can I say. Hope this info will help others who have fuel delivery issues. The problem was a weak fuel pump, probably also sucking in air, worse when under half tank. Some of the things that I did was to compare it's performance to my 97 aerostar. As stated before, I only got 3 or 4 ounce of fuel from the problem 96 areo, but i tried the 97 and got 12 oz in 15 secs. The pump, complete, was 120 , dropping the tank, a snap. 5 fasteners on the heat shield, 2 on the tank straps and one clamp on the fuel filler. Didn't even need any Jack to lower the tank. Did have one but removed it because this plastic tank with a couple gallons in it was not a problem. It was difficult to diagnose this issue since so many things can give you the symptoms. Plus with 14 year old aero that no one wants to service because it is difficult. Had 1 ase mechanic service it but was not addressing the issue successfully. At least now I do have new coil pack, probably the only item that was not bad,wires and plugs, water pump, new tps and act and great brakes all around. By the way, I did back the van onto my ramps to drop the tank, all went well. Thanks BrooklynBay for helping me narrow this issue down. I still believe the aerostar is the best work vehicle. Maybe i'll find the time to post pictures of my 3/4'' pipe rack the i've had on all three of my aeros that I have loaded to the max without problems. I'm talking 30 sheets of 1/2'' ply on my roof.Not to mention loads of treated 2x6 for decks. Just a carpenter in Texas. Dennis.......

 

[BrooklynBay]

Thanks for the update! You said that the pump with the sending unit was $120. Did you purchase a new one or transfer the one from the 1997? How did you hold the tank without a jack? Did you take pictures while removing & installing the tank?

 

[musicman76]

pump follow up

No pics of the change out. Purchased a new pump at autozone for 120 complete. Had to get it from another store 30 miles away but got it in 3 hours. Too bad I didn't notice when i took back the pump and strainer only, that the assembly didn't come with the strainer. Sent my wife to get the strainer, called them first to let them know what i still needed. Still, she came back with all that I had returned 3 hours earier, go figure. The job was quite easy and dropping the tank to the floor was easy, plenty of play with the electric and fuel lines to disconnect on the ground. Tank was absolutely clean so no need to empty. I did however, use my jack to get it back into position. If I had a helper with me, I wouldn't even have had to do that. It really was easy to do. Today, I changed out the rack and pinion on my 91 mustang, what a pain in the ass this has been. But, that's another story! Thanks...

 

[BrooklynBay]

There were two tank sizes I believe, a 17 gallon & 21 gallon. I hope that they gave you the correct sending unit. Since the pump from the 1997 was good, why didn't you use that? What's the brand of the new pump? Did you check the fuel pressure of the new pump? Did you replace the fuel filter?

 

[musicman76]

Why?

i didn't use the '97 for many reasons. One is that I need to move that van as the house where it is kept has finally been sold. 2nd is your answer that it would just add to my labor.3rd is because it's been raining here all week and it's in a driveway. Have a '91 Mustang in that garage which I have to finish the rack replacement on before I can move it to my house. Have been kicking the idea around about takink the 4 litre and putting it in the mustang since it is a 2.3 4 banger. Mechanic says to get a 302 instead. I like a challenge though. Here it is, raining again! But we need it, lost millions of trees last summer here in the Houston area but there are plenty more to take their place. Just culling out the week ones. Oh, the new pump is an airtex. Later.