94 Dutch Star 460 struggles under load

[Dfrnt]

24,000 miles. It doesn't seem to want to take more than half throttle without sounding like it's bogging down and picks up speed very slowly. When you let off the gas, the engine perks right up. Changed the fuel filter without any improvement. I have 30psi fuel pressure which is barely within spec of 30~45psi. Drove down the road with the gauge attached and when I hammer it the fuel pressure drops to 22psi. The pressure regulator seems to be working alright according to Mr. Haynes and his manual. I am getting too much pressure drop after turning the fuel pump off so I suspect a sticky injector. Fuel pump time?

[tnarvs]

I would say that it is time for a fuel pump ,, one thing ,, did u take the vac line off the regulator and see what the pressure was ,, but as u stated " it was barley with in specs" i have seen fuel pumps that are close to recommended pressur ,, but the volume is very low ,, there is a test for volume that u can do ,, u will have to ck the manual to see what it is ,, but the way u have stated it ,, sounds like a fuel pump

[Muddypaws]

Fuel filter, fuel pump, in-tank fuel pump. But what you describe in the first sentence said manifold leak or clogged catalytic converter to me.

[ddev]

Plug wires maybe? Dropping a cylinder or two under load. I was thinking converter too.

[Dfrnt]

Originally Posted by tnarvs

I would say that it is time for a fuel pump ,, one thing ,, did u take the vac line off the regulator and see what the pressure was ,, but as u stated " it was barley with in specs" i have seen fuel pumps that are close to recommended pressur ,, but the volume is very low ,, there is a test for volume that u can do ,, u will have to ck the manual to see what it is ,, but the way u have stated it ,, sounds like a fuel pump

I did take the vacuum line off of the pressure regulator and the pressure increased by 10psi. The manual states that it should increase 5~10 psi so that is why I believe that the regulator is okay. I'll see if I can find out what the gallons per minute should be tomorrow but I got fed up with it tonight. Thanks for the help.

[Dfrnt]

Originally Posted by Muddypaws

Fuel filter, fuel pump, in-tank fuel pump. But what you describe in the first sentence said manifold leak or clogged catalytic converter to me.

I started with fuel delivery and vacuum (which is steady at 21 in Hg) and haven't really given a thought to exhaust restriction yet. I don't believe it could be related to a drop in fuel pressure so I at least need to figure out what is going on there. My understanding is that when the throttle opening increases, so should fuel pressure. Mine is going the other way. I'm assuming you are talking intake manifold which I believe should show up as a vacuum leak or drop, which it doesn't. I know that I prefer working on my motorcycles, especially the non fuel injected ones. A lot simpler.... Thanks for your thoughts.

[Muddypaws]

OBD and OBD2 are not good at detecting/reporting manifold leaks. But there is a very simple test for manifold leaks. All you need is a squirt gun or bottle.

With the engine idling squirt water around the base of the intake manifold and everywhere there is a connection, including vacuum lines that go to things like the climate controls, transmission etc.

If the idle changes when you spray something you've found a leak.

Ford replaced my transmission, 2 injectors, and several other things and finally gave up and advised me to sue them under the lemon law. My father-in-law was an old school mechanic and told me to try the spray bottle. He was right as it had no fewer than 3 leaks at the manifold base. New gasket solved the problem.

Our 92 Honey was on it's 4'th catalytic converter when we got rid of it. I became very familiar with what a clogged one felt like. But they usually only clog up when very hot. How does it run when cold?

[Dfrnt]

Originally Posted by Muddypaws

OBD and OBD2 are not good at detecting/reporting manifold leaks. But there is a very simple test for manifold leaks. All you need is a squirt gun or bottle.

With the engine idling squirt water around the base of the intake manifold and everywhere there is a connection, including vacuum lines that go to things like the climate controls, transmission etc.

If the idle changes when you spray something you've found a leak.

Ford replaced my transmission, 2 injectors, and several other things and finally gave up and advised me to sue them under the lemon law. My father-in-law was an old school mechanic and told me to try the spray bottle. He was right as it had no fewer than 3 leaks at the manifold base. New gasket solved the problem.

Our 92 Honey was on it's 4'th catalytic converter when we got rid of it. I became very familiar with what a clogged one felt like. But they usually only clog up when very hot. How does it run when cold?

Manifold gasket affects the vacuum right? Vacuum checked fine. Hot or cold it runs the same. I thought initially that it was the tranny but remembered what an old mechanic told me once about making sure the engine was running right first, so that's why I started with fuel supply. Can't really test drive it right now as one of the 6 brand new tires installed yesterday is flat. I am planning a weekend trip this Friday so I may have to give up and get the tire fixed tomorrow and drive it to the repair shop. If it is the fuel pump I don't really feel up to it today. 65 gallons in the tank that would need to go somewhere.

[Wanabee FTer]

Originally Posted by ddev

Plug wires maybe? Dropping a cylinder or two under load. I was thinking converter too.

No cat converters on F-53 Ford chassis until 1999.

Originally Posted by Dfrnt

If it is the fuel pump I don't really feel up to it today. 65 gallons in the tank that would need to go somewhere.

Early Ford in tank fuel pumps were prone to failure. If you replace fuel pump I would recommend to update to the newer style turbine fuel pump per Ford TSB# 97-23-9

Just curious, was the MH stored for the winter with full tank of gas?

[JohnRR]

Originally Posted by Muddypaws

But what you describe in the first sentence said clogged catalytic converter to me.

My first thought when reading it as well.

Originally Posted by Wanabee FTer

No cat converters on F-53 Ford chassis until 1999.

Over the years I've seen more than 1 Ford V8 display cat failure symptoms only to turn out to be a bad Y pipe where it was welded at the Y itself, by the 94 model year for this chassis they were welding the left & right pipes to a flat flange instead to eliminate the problem. I can not begin to think of how many clogged mufflers fell into that category as well. Look around the outside of the muffler for different discoloration patches (many times white color looking).

When it starts to bog down let off the gas pedal for about 10-20 seconds then try accelerating again if it runs good before bogging down again the exhaust is where I would look. Also if it bogs down when climbing a hill let off the pedal to let some exhaust pressure out and try climbing the hill with less throttle pressure.

If exhaust gases can not get out of the engine then you can not get a fresh gas charge into the engine which is why it acts as if it's not getting any gas.

[Dfrnt]

Originally Posted by Wanabee FTer

No cat converters on F-53 Ford chassis until 1999.


Early Ford in tank fuel pumps were prone to failure. If you replace fuel pump I would recommend to update to the newer style turbine fuel pump per Ford TSB# 97-23-9

Just curious, was the MH stored for the winter with full tank of gas?

Just bought the MH 3 weeks ago and it had been sitting over the winter. Had less than a 1/4 tank when I got it. Filled it up and ran most of that out on the way home and filled it again. Thanks for the tip on the updated fuel pump. I'll make sure my guy puts that one in if it needs one.

[stan4x4]

I have a 94 holiday rambler 34' 460 with 25 thousand miles on the way home from florida last month my engine would die when you got off hwy on hot days let it cool it would start up get on hwy and it would run ok finaly made it home checked fuel pressure and it was low droped the tank and installed new pump airtex # E2063m fit right in and the pressure was ok it did not seem to loose power it just vaporlocked when you came off hwy after 1 to 3 hours of driving, in the evening and at night it was ok the outside tempture was lower, my tank has a flange on each end i took the bolt out put in some allthread took the straps off and lowered it down with the allthread had to lean tank a lot to get the filler neck to pass the frame it was not to bad a job, pulled it one day put it back in the next went in better than came out.

[Dfrnt]

Originally Posted by stan4x4

I have a 94 holiday rambler 34' 460 with 25 thousand miles on the way home from florida last month my engine would die when you got off hwy on hot days let it cool it would start up get on hwy and it would run ok finaly made it home checked fuel pressure and it was low droped the tank and installed new pump airtex # E2063m fit right in and the pressure was ok it did not seem to loose power it just vaporlocked when you came off hwy after 1 to 3 hours of driving, in the evening and at night it was ok the outside tempture was lower, my tank has a flange on each end i took the bolt out put in some allthread took the straps off and lowered it down with the allthread had to lean tank a lot to get the filler neck to pass the frame it was not to bad a job, pulled it one day put it back in the next went in better than came out.

Brilliant tip on the all thread. Wished I'd thought of that this morning. I would have probably dropped it myself. On second thought, no I wouldn't have. I'm already ticked off enough with this project. If I had another week, maybe.

[Wanabee FTer]

Originally Posted by Dfrnt

Just bought the MH 3 weeks ago and it had been sitting over the winter. Had less than a 1/4 tank when I got it. Filled it up and ran most of that out on the way home and filled it again. Thanks for the tip on the updated fuel pump. I'll make sure my guy puts that one in if it needs one.

Seems to be a common denominator, storing for winter with low fuel tank will eventually cause the fuel pump commutator to corrode.