Engine is very hard to start, but once in drive & moving it runs smooth

[FullMetalEngineer]

Hello All,

I am new to the forum and I am embarking upon my first vehicle restoration project. I am fairly new to mechanical repair, so if I ask a dumb question, just be aware that it's because I haven't done this very much.

The Vehicle
I recently purchased my great-great-grandmother's 1972 Ford F-100. It's a 302 V8, 2wd, two-tone green, and is still in fairly good condition given its age and the fact that it hasn't been ran in 7-10 years.

What I did to get it running
First thing was replace the battery. Second was to replace the radiator hoses, as they had begun to swell. Third was to fill all of the fluids that I can, although I have not yet replaced the oil (I was just trying to get it running & home). At this point, we got it going by pouring gasoline into the carburetor to prime it.

The Problem
Once I get the truck 1) running and 2) moving, it runs smoothly. I drove it quite far towards my home, about 50 miles, doing 55-60 mph. The issue is when I 1) slow down or 2) attempt to start the truck and put it into drive or reverse.

If I am already moving and I slow down to say, 25 mph or below, it dies on me. If it is not running and I try to start it, I can often get the truck started and idling, but when I put it in drive or reverse, it dies as soon as I shift.

I am guessing that this is something wrong with the carburetor. I have tried mixing seafoam into the gas, in both the gas tank and in the mixture I was priming it with. That didn't seem to work. I am guessing that I will need to clean the carburetor or replace it entirely. However, might there be other things causing this problem that a newbie like myself not think of?

Lastly, below the driver's side seat, there is a small bit of gas line that is exposed. Gas was leaking from a hole in this that had previously been sealed over with a rubber piece. I solved it long enough to get home by wrapping a piece of rubber tightly around the leak and clamping it with a circular clamp, not too tight, just enough to stop the leak. Can the gas line part that is exposed by replaced easily, or will I have to replace the entire gas line? Is that something that an amateur like myself could do?

Eventually, I will probably replace nearly all of the hoses & wiring underneath the hood to ensure that it runs well into the future, but for now I'd just like to get the thing running properly. I have a cousin who mentioned that the engine problem could be due to vacuum tubes, but I do not know what those are nor have I been able to locate a good diagram on them.

If you have any advice or questions, I'd be more than glad to hear from someone with a little experience in this realm.

[Ohiotinkerer]

I'm surprised it would run down the road after sitting that long.........I've NEVER had that happen!.....
After setting for that amount of time I would pull and clean the tank, replace the fuel lines and any fuel filter it may have, clean and rebuild the carb, replace the vacuum lines, plugs, wires, and points and see where that gets you. Not that expensive to do and that will eliminate the simple stuff. Post up some pictures too!.......

If I can find it I will add a link to the vacuum hose routing.........if one of the other fine people here doesn't beat me to it!....

[1972hiboy]

hehe vacuum tubes, your cousin must work on radios, Vacuum lines should be gone after for sure, they get hard and brittle with age, I would assume a carb rebuild is a must after sitting that long. also check the modulator down on the transmission. If its leaking its a vacuum leak.

[71Fe2O3]

I am amazed that you drove that thing home-I don't think I would have chanced it.

Vacuum tubes, I like that. Perhaps you could tune the radio just right and get repair advice from Henry himself. Your truck has vacuum lines, but no tubes.

Your symptoms seem to implicate the carburetor and/or vacuum lines. An engine that old can have many weak points that will in time make themselves known in ways that may be obvious or subtle.

Here are my recommendations for things to take care of right away in order to get your engine running reliably.

Fuel delivery-replace the fuel filter-one with a clear housing will allow you to monitor the buildup of sediment and replace it before it clogs. Replace the various fuel lines and clamps-under the hood, in and under the cab. Rebuild the carburetor or have it done, then mount it up and get it properly adjusted-you can find information here and elsewhere to help with that. Replace the fuel pump. It contains a rubber diaphragm that gets brittle and breaks, flooding the crankcase with fuel.

Engine electrical-new plugs, wires, cap and rotor, points and condenser. Make sure electrical connections are clean. Consider replacing the starter solenoid and voltage regulator in the near future.

Engine vacuum and ventilation. The number of vacuum lines depends on the specifics of your vehicle. At a minimum yours should have one from the carburetor to the distributor. Automatic transmission and power brakes will add additional lines. The PCV system also operates on engine vacuum.
Replace PCV valve, check PCV system for leaks and clogs.

With an old vehicle you never lack for ways to spend your time and money. Good luck with it.

[FullMetalEngineer]

Thanks y'all, I think I have it now - it's "Vacuum lines," not "vacuum tubes." I told y'all I was new to this!

Here's what y'all have suggested so far, and probably the order I'll tackle this in:

• Rebuild/Replace the carburetor

• Replace the vacuum lines

• Replace fuel filter & pump with a clear one

• Clean the gas tank

• Replace the fuel line

• Check PCV system for leaks or clogs

Does this look like a reasonable order of operations to get this thing on the path to running again? As for the PCV, which someone above mentioned, what exactly does that do? Are there any good diagrams depicting it, or photos showing what it looks like/where it is located?

As for photos, here ya go! That's a link to a gallery of images I just took of it.

http://imgur.com/a/aGcJO

[colnago]

The PCV basically recirculates the crankcase gasses back into the intake. Some people just vent them to the outside. I found that mine had problems when I did that (condensation built up in the crankcase, and caused my mechanical fuel pump to stop working), so I had to route it to the intake. The valve is usually on the back of one of the valve covers, and is routed to the intake or carb (mine goes to the carb, but that's because it was convenient). The PCV valve itself is pretty simple: basically, a tube with a marble inside to keep gasses going from the intake to the crankcase. It's a pretty simple circuit. You can probably find something on google.

Your order is pretty sensible. You're going to want to do all of this anyway. I expect if it's been sitting, any gas in the carb has long turned to varnish and clogged some of the smaller jets. Suspect anything that's rubber. With the fuel filter and pump, the poster was talking about two separate items. I had my clear filter on top of the intake, so I could make sure that fuel was flowing, and I wasn't getting crud in the line. My neighbor had his down on the side. You can really put them anywhere. Make sure you get the right size, because different years have different size fuel lines (I want to say 5/16" and 3/8", but it's been too long; hopefully, someone will correct me). The pump sits lower, on the driver side of the engine. It's right at the front, so it's really simple to swap out. The filter is less than ten bucks; the pump is probably fifty-ish.

Keep us posted.

Joseph

On edit, when I was a kid, some people still had electronic devices with vacuum tubes. I remember our local Thrifty Drug Store had a tube tester in the front of the store, right next to the ice cream counter (ten cents a scoop, three scoops for a quarter).

[FullMetalEngineer]

Your order is pretty sensible. You're going to want to do all of this anyway. I expect if it's been sitting, any gas in the carb has long turned to varnish and clogged some of the smaller jets. Suspect anything that's rubber. With the fuel filter and pump, the poster was talking about two separate items. I had my clear filter on top of the intake, so I could make sure that fuel was flowing, and I wasn't getting crud in the line. My neighbor had his down on the side. You can really put them anywhere. Make sure you get the right size, because different years have different size fuel lines (I want to say 5/16" and 3/8", but it's been too long; hopefully, someone will correct me). The pump sits lower, on the driver side of the engine. It's right at the front, so it's really simple to swap out. The filter is less than ten bucks; the pump is probably fifty-ish.

Actually, it looks like that has already been done by my grandfather, who inherited this truck after my great-great-grandmother passed. He told me it has barely been ran in 5-10 years, but I do know that he put a new radiator in it approximately 2 years ago, and it appears that he put a new fuel pump and filter in it too (but he didn't mention that to me).

Photo of the fuel pump:
https://i.imgur.com/5YsVzk1.jpg?1

Photo of the clear fuel filter:
https://i.imgur.com/NpIqN5q.jpg

[colnago]

Do you have a hose clamp on the intake to your filter? I couldn't tell from the photo. If not, you might be sucking air into the line. I think I have an air leak somewhere in my fuel line, which makes it harder to start in the morning. It's low priority right now, though, so I live with it.

Joseph

[FullMetalEngineer]

Do you have a hose clamp on the intake to your filter? I couldn't tell from the photo. If not, you might be sucking air into the line.

I believe there is one there, but I'll have to check that again later when I'm off work.

[Ohiotinkerer]

On edit, when I was a kid, some people still had electronic devices with vacuum tubes. I remember our local Thrifty Drug Store had a tube tester in the front of the store, right next to the ice cream counter (ten cents a scoop, three scoops for a quarter).

Nice to know I'm not the only one old enough to remember that...........

[MadJoe]

Thanks y'all, I think I have it now - it's "Vacuum lines," not "vacuum tubes." I told y'all I was new to this!

Here's what y'all have suggested so far, and probably the order I'll tackle this in:

• Rebuild/Replace the carburetor

• Replace the vacuum lines

• Replace fuel filter & pump with a clear one

• Clean the gas tank

• Replace the fuel line

• Check PCV system for leaks or clogs

Does this look like a reasonable order of operations to get this thing on the path to running again? As for the PCV, which someone above mentioned, what exactly does that do? Are there any good diagrams depicting it, or photos showing what it looks like/where it is located?

As for photos, here ya go! That's a link to a gallery of images I just took of it.

http://imgur.com/a/aGcJO

All great places to start, but also don't forget to replace plugs and wires, cap and rotor, and probably most important: Points! Just go ahead and eliminate them by installing a PerTronix Igniter. My points were $45, the Igniter was $65. That extra $20 was the best $20 I have spent on this truck to date, and like you I've only been trying to 'get her back to running good'.

What I've done to my 360 so far is:

• Replaced plugs and wires

• Replaced the in-line fuel filter with the glass tube type

• Cleaned the carb with a few squirts of carb cleaner and adjusted the choke

• Changed the oil and filter

• Installed the Igniter (only thing to make a real difference so far)

• Ran Seafoam through her

• Tossed some Royal Purple engine cleaner in the gas

• Replaced Cap and Rotor

Just my

-Joe

[FullMetalEngineer]

Hey all,

Got another few questions.

I believe this is the PCV. It has a hose that runs around to the back side of the carburetor.
https://i.imgur.com/UciplcH.jpg

Does anyone know what this piece is? It's off the passenger back side of the engine, but there is no hose connected to it.
http://imgur.com/ByYzphv

Just trying to get acquainted with what everything is and does on this thing. Takes awhile to learn this stuff!

[Ohiotinkerer]

You're on the right track - that is the PVC valve! The 2nd one I'm sure is a vent that should fasten to the air cleaner on the outside...not exact of what its called but from that fitting on the end I'm sure that's where it goes.....good thing about here is if I'm wrong someone will correct me!...... Been a long time since I've worked on a stock 302 so I'm going off memory.....and it ain't as good as it was!

[markguiver]

The hose that is not connected to anything is supposed to be connected to a fitting on the stock air cleaner. That allows fresh, filtered air into the crankcase for the PCV system. If you scroll down to the Diagrams and Schematics heading, click on the Engine section, then scroll down to the Emission reduction system and open it. That will give you a general idea of what the system is supposed to look like. It doesn't look like the system on your motor has a PCV valve in it. Another thing I see is the rust on the choke plate and wondering what the inside of the carb looks like.
Mark.

[71Fe2O3]

The PCV system is designed to vent gases from the crankcase into the combustion chambers where the hydrocarbons they contain (unburned fuel that gets past the rings, as well as oil vapors) are burned. The valve itself is designed to allow gases to flow in one direction (from crankcase to intake) and prevent backfires from the intake from igniting the gases in the crankcase. It is actually more complex than a marble in a can, but that is the basic idea.

Because the gases in the PCV system contain unburned fuel they are significant sources of pollution and should not just be vented into the atmosphere. On the other hand, blockage in the PCV system can restrict the flow of gases out of the crankcase and cause engine damage.

For the system to work properly, air must enter the crankcase to replace the gases that leave. In some trucks the incoming air is crudely filtered by metal mesh in the oil cap. In modern vehicles, the incoming air is routed through the engine air filter in order to minimize the amount of dirt entering the crankcase. The system in yours was apparently designed to take air in through a filtered port in the side of the engine air breather. That is where the plastic fitting on the end of the hose in your second picture would go.

At the other end, crankcase gases leave through the PCV valve, which, in your truck, should be in the oil filler cap in your first picture, then pass through the attached hose into the back of the carburetor riser.

Someone else may know better, but I think that the PCV routing on your truck is not stock for the 67-72 trucks, which suggests to me that your engine, or at least the PCV system plumbing, is of a more recent vintage.

In my trucks (one has a 302, the other a 360), the incoming air enters the crankcase via the oil filler cap on the front of the driver's side valve cover, and the PCV valve fits in a grommet-containing cap on the rear of the passenger's side valve cover. It is the reverse of yours in terms of flow, and has the benefit, in my opinion, of not needing a hose attached to the oil filler cap or the other hose to the air breather. Your valve covers should be the same, so if you can find the valve cover caps you could simplify your setup.