87 F150 Won’t Start

[RonD]

Back port on the PCM is for programming, its not used for operation

Do you have the vacuum hose hooked to FPR(fuel pressure regulator), its a direct hose to intake vacuum
If needs that to pull down fuel pressure at idle
But FPR may be failing as I would expect it to top out and open on its own at 65psi

In 1987 I would expect EVAP to be that way, no purge valve or pressure sensor
throttle body port------------CCAN------------gas tank
Simple system

One its up and running and you get any Codes for EVAP then it may need those, but for now just see what happens, it won't effect engine operation, its strictly a fuel vapor emissions system

 

[Mhfco6]

Back port on the PCM is for programming, its not used for operation

Do you have the vacuum hose hooked to FPR(fuel pressure regulator), its a direct hose to intake vacuum
If needs that to pull down fuel pressure at idle
But FPR may be failing as I would expect it to top out and open on its own at 65psi

In 1987 I would expect EVAP to be that way, no purge valve or pressure sensor
throttle body port------------CCAN------------gas tank
Simple system

One its up and running and you get any Codes for EVAP then it may need those, but for now just see what happens, it won't effect engine operation, its strictly a fuel vapor emissions system

Yes I installed the original hose back on the FUEL pressure regulator, felt like it might have been collapsing my new rubber lines. Truck would not start again, so don’t know if it was the line collapsing or the fact I put a gallon of gas in the tank.

New fuel pressure gauge reaches 85 during idle then levels out there.

It is up and running now, set timing marks accordingly. Idle is alittle high I noticed someone may have fiddled with the throttle body stop screw and bent the stop bar. I opted to bend the stop bar back a bit instead of fooling with the broke screw. It’s running good now, just idles a bit fast. Now I’m having a rough starting issue like the timing is off yet again, or the battery is low. I pulled a volt and amp test on the battery and terminal wires, all checks out 12+.

I do not have a check engine light as of now, and the light illuminates when truck is first started.

 

[RonD]

85psi is way too high, test that gauge on a tire with known pressure

 

[Mhfco6]

I

85psi is way too high, test that gauge on a tire with known pressure

It should be a good gauge, I test waterlines with these gauges, it is new though. Anything is possible though.

 

[Mhfco6]

I swapped the gauges, and tested the new gauge. New gauge read fine and duplicated a tire pressure at 32 psi. Original Pittsburgh gauge was reinstalled and read 80+psi again after about 10 mins. After about 15 mins gauge had crept up to 90psi, so I shut the truck off. Any ideas whats causing the high pressure?

My sticker in the drivers door has very little info on the transmission. All it has is an F. I took a picture of the trans tag also, but couldn’t correlate anything to that group either. Can anyone tell me if this trans take gear oil or atf?

I need to install a tach to check my idle, it’s still a little high. Anyone know what the RPM is supposed to be at idle? 600-700?

 

[RonD]

Rear axle code 19 is a 3.55 OPEN

Trans code F should be a 4-speed Borg-warner T-18, use 80w90
Transfer case should be a BW 1345, use Mercon V or the Ford Transfer case fluid


As for the fuel pressure it is running at pumps maximum pressure so something is blocking the return to the tank, could be in the fuel rail, the FPR or the return line, or even in the tank

I would take off the return line at the engine end and blow thru it to make sure its OPEN, no restrictions

 

[Mhfco6]

Rear axle code 19 is a 3.55 OPEN

Trans code F should be a 4-speed Borg-warner T-18, use 80w90
Transfer case should be a BW 1345, use Mercon V or the Ford Transfer case fluid


As for the fuel pressure it is running at pumps maximum pressure so something is blocking the return to the tank, could be in the fuel rail, the FPR or the return line, or even in the tank

I would take off the return line at the engine end and blow thru it to make sure its OPEN, no restrictions

Never even thought of that. I browsed the idea of the selector valve being trashed again, I bet that’s the problem. Figured since it was getting fuel it was working properly. I remember someone saying their return was actually filling the opposite tank that was selected. I have the front tank removed still, I can easily see that’s not the issue.

I took the selector valve off again. Fuel pressure is still holding at 55 psi. I do not have fuel coming from the tank.
I will be getting a new fuel pump, but why does the gauge still have 55 psi. Does the pump hold the pressure in on the rail side?

 

[Mhfco6]

New in tank pump and bypassed the selector valve. All is right again.

 

[Mhfco6]

Truck had a leak on the return line clip when i installed the new in tank pump, so I know fuel is coming back to the tank. However, I still have PSI over 75 on my gauge on the fuel rail

 

[RonD]

If you have fuel coming back to the tank then FPR(fuel pressure regulator) is set for 75psi
Does pressure drop if you suck on the FPRs vacuum hose, it should drop
FPR gets full intake vacuum with engine running, so 18-20" at idle
But that should only drop it maybe 10psi

 

[Mhfco6]

If you have fuel coming back to the tank then FPR(fuel pressure regulator) is set for 75psi
Does pressure drop if you suck on the FPRs vacuum hose, it should drop
FPR gets full intake vacuum with engine running, so 18-20" at idle
But that should only drop it maybe 10psi

If I disconnect FPRegulator vacuum hose at manifold tree and suck, the gauge doesn’t do anything. The gauge seemed to stay around 80 for a long time. Had the truck idle and went for a very short cruise.
Trans is making an intermittent noise when coasting and taken out of gear. Sounds like a familiar bearing grind I had in an old corolla.

 

[RonD]

Did the FPR HOLD the vacuum?

Vacuum is not "used up", vacuum devices don't need continual suction, you pull a vacuum(suck on hose) and then it should hold that vacuum until you release it out of the hose

In the real world vacuum is lost over time, lol, but not in short term testing
Like a power brake booster should hold enough vacuum after engine is off for 3 pedal pushes, and it will hold it for days, like when you get in your vehicle to start it, after several days of sitting, and put foot on the brake pedal it goes down easily because you still have vacuum in the booster

 

[Mhfco6]

Did the FPR HOLD the vacuum?

Vacuum is not "used up", vacuum devices don't need continual suction, you pull a vacuum(suck on hose) and then it should hold that vacuum until you release it out of the hose

In the real world vacuum is lost over time, lol, but not in short term testing
Like a power brake booster should hold enough vacuum after engine is off for 3 pedal pushes, and it will hold it for days, like when you get in your vehicle to start it, after several days of sitting, and put foot on the brake pedal it goes down easily because you still have vacuum in the booster

The hose I pulled off the tree wasn’t sucking or blowing air at me, if that’s what your asking. The tree itself on the manifold was sucking air once I pulled the hose off. So I pulled a draw on the hose coming from FPR, stuck my tongue over the hose opening and the air was kept in the hose until I removed my tongue. Hope that makes sense and this is the info you need.

 

[RonD]

Yes, then FPR was holding a vacuum

But unless its the wrong FPR its broken, the Fuel Pressure "REGULATOR" sets the maximum fuel pressure which for the 1987 4.9l was 55-60psi

 

[Mhfco6]

Yes, then FPR was holding a vacuum

But unless its the wrong FPR its broken, the Fuel Pressure "REGULATOR" sets the maximum fuel pressure which for the 1987 4.9l was 55-60psi

Just cleaned her up and went for a cruise, popped the hood to check fuel pressure. Was 82psi, I started typing this post and take a picture and it was like this at 100.