Question Fuel pressure issue

[skinlance]

Hello my name is skinlance I am having a problem with fuel presure on my 1989 ford e350 motorhome 460 efi
I put a fuel cooler on and a fuel presure regulator and now my fuel presure stays at about 30 to 34 at iddle and running.
Not sure what to do
thanks Dave

 

[BGMAC]

That sounds normal to me.

 

[GypsyR]

A fuel cooler? Little odd. But anyway, I prefer my fuel pressure to be more like 40 psi. I bought an adjustable fuel pressure regulator to get that. Bonus is that it has a port on the side where you can put a fuel pressure sensor so you can add a gauge to the dash. For a while I had a mechanical gauge on the fuel rail and the gauge sticking out of the engine cover.
All that said, 30-34 at idle doesn't sound too concerning, what is it at full throttle going up a hill? THAT's where I want good fuel pressure. Revving it up in Park doesn't tell you anything.

 

[skinlance]

That sounds normal to me.

I just installed a fuel line cooler and was wondering if that had anything to do with the lower than normal presure?
Last week It was 30 to 35 ignition on and 45 to 55 running now it is lower was just curious.

 

[GypsyR]

45-55 is too high. My max is right at 40 these days. I experimented with the tuning of my slightly higher capacity injectors and up to 43 psi on the fuel but the air fuel ratio readings didn't reflect that the higher than stock fuel pressure was beneficial.
I don't get the fuel cooler. My fuel is cooled pretty well I think by being in a 75 gallon tank and then running up a 20 foot fuel line to the engine. Fuel coolers are more a diesel thing in my experience. What kind did you use?

 

[skinlance]

A fuel cooler? Little odd. But anyway, I prefer my fuel pressure to be more like 40 psi. I bought an adjustable fuel pressure regulator to get that. Bonus is that it has a port on the side where you can put a fuel pressure sensor so you can add a gauge to the dash. For a while I had a mechanical gauge on the fuel rail and the gauge sticking out of the engine cover.
All that said, 30-34 at idle doesn't sound too concerning, what is it at full throttle going up a hill? THAT's where I want good fuel pressure. Revving it up in Park doesn't tell you anything.

It all started in August driving to the east coast In the begining of August I had an overheat problem on an 5 hour trip. Limped my way for about another hour or so. Then it would not start. waited for the tow truck (CAA) We were 1 and a 1/2 hours from Edmunston New brunswick.Four hours later the tow truck showed up. The driver jumped out of his truck with a battery operated sawsall. I tried asking what was going on he only spoke French and I sadly never learned to speak french. he just kept pointing and pulling the trigger. His girlfriend finally came and she spoke english. she told me he was going to cut out the drive shaft to tow it and he could only tow us to the quebec and new brunswick Border as his licence won't allow him to drive in new brunswick. I told him ro leave as I was not getting standded on the border with out a drive shaft. so i tried starting it and after a few time it started up and ran great for the 1 1/2 hours to the comfort in parking lot. got a mechanic to look at it and he said it needed the in tank fuel pump and the rail pump he tried explaining but again very broken english. parts labour and taxes $3200.00 and when i asked for a copy of the invoice he proceeded to yell at me over and over so I paid and just left. we made it for about two hours and the same thing happened. when we went to get off the highway it started dying like it wasn't getting gas. called the mechanic and he started yelling in english (Suprising how fast he learned the language) saying he did his job must be something else and hung up. so we waited for a few hours and again it started we made it to a canadian tire parking lot. Called a few ford machanics. everyone of them saaid something differant. so I just went and ordered Distributor (and thus PIP sensor) Ignition Control Module Engine Temperature Sensor Idle Air Control Valve Fuel Pressure Regulator Plugs and Plug Wires Fuel Filter High Pressure Fuel Pump (mounted on frame rail). also installed an in line fuel heat exchanger on the return line. Ever since then, when there were high ambient temperatures, if I was running down the road everything was usually fine, but if I slowed down due to traffic or getting off the highway onto a surface street the RV would die as if it was out of gas. Trying to start it would result in it sputtering like it was trying to catch, but it would not. Sometimes it would start, barely, but die on idle very quickly. I assumed that there was some "cooked" component on the engine that had been damaged during the overheating in Agust. So, based on lots of "internet" advice on what could be wrong, I spent a lot of time and money, and still the same problem. Any help would be much appreciated. My head is getting all banged up, Banging it against the wall. Sorry for all the Ranting Skinlance (Dave)

 

[Kevin D Pem]

Ok! First advice is quit looking at your EFI as though it had a carburetor!

Is there a vacuum line on the regulator?
What kind of pressure does the fuel pump produce?
Have you checked the MAF/MAP SENSOR.

Have you checked the ambient temperature sensor. Have you checked engine temperature sensor (the on that goes to the computer)?

Have you checked/replaced any fuel filter? Depending on model, there may be an inline filter.

It's all about parameters, you need to verify those or empty your purse.

 

[Joe Hogan]

Maybe vapor lock if it is heat related.
If everything works when cool but acts up when hot, especially after the engine heat soaks. My experience points to vapor lock.

 

[GypsyR]

Sounds like you bought out the parts store. I'd say you need to find a gray haired Ford technician who knows and remembers the 1980's trucks to do some actual diagnostic work. I know those are very hard to find, but still....
Not sure why one would put a fuel cooler on a return line whose function is merely to dump excess fuel back into the tank, but anyway. Do you have an OBD I Ford capable scanner? I find them worth their weight versus counting light flashes and then looking up what that might mean. The code functionality is pretty limited on an '89 but still it's where I would start.

 

[Joe Hogan]

Vapor Lock and Hot Fuel Problem Solution

www.460ford.com

 

[GypsyR]

Highly unusual to see vapor lock on EFI engines. Note the link to the thread above is all about a person with a CARBURETED 460 and about nothing he did and experienced applies to a fuel injected 1989 model. The 4.9 engines had some issues as the injectors were placed unhappily close to the exhaust manifold. To combat those issues Ford had a fan that blew fresh air onto them and also ran higher fuel pressures. But again, a different engine and does not apply here.

 

[Kevin D Pem]

Highly unusual to see vapor lock on EFI engines. Note the link to the thread above is all about a person with a CARBURETED 460 and about nothing he did and experienced applies to a fuel injected 1989 model. The 4.9 engines had some issues as the injectors were placed unhappily close to the exhaust manifold. To combat those issues Ford had a fan that blew fresh air onto them and also ran higher fuel pressures. But again, a different engine and does not apply here.

Agreed! Here is a chart that puts that issue up front, and on the table! They cured vapor lock when they put the pump in the tank!!!

 

[Joe Hogan]

Guys, I agree that FI engines are less likely to suffer Vapor lock. It sure sounds heat related rather than random debris blocking fuel. Pressure regulator too hot?
When the engine will not start you might loosening a return line to see if fuel is flowing. Or better yet put in a pressure gauge inline to see the changes between running condition and not. Have an extinguisher nearby just in case.

 

[Kevin D Pem]

Temperature related, yes! Faulty pressure regulator! Maybe. Checking pump pressure, definitely.

I will stick with Temperature sensors. (Ambient, and engine). They regulate injector timing (fuel mixture). MAP sensor/air flow sensor??? That would show up on the O2 sensors.