Discussion in 'Classic Mustang Specific Tech' started by mustangman1974, Jul 26, 2008.
Edit: on second thought - deleted post.
Try what I mentioned, which is to spray water at the fuel lines and see if the pressure goes up and stumbling goes away.
Here's an 'out of the box' suggestion.
Drain your gas tank and get new gas and see if the problem goes away. Bad gas - just a thought.
been through about 20 tanks since the problem, but not to far from what I am gona try next.
Some no car guy today while endulging in some good beer a light came on. I know it has to be a fuel delivery problem. To eliminate a fuel line or tank issue, without training. I am going to hook up a fuel line from the pump to the gas can. if it don't happen then I have to drain the tank and check the sock and pickup. If it does then I can try my electric pump with the same configuration. IF it continues then I have eliminate the fuel delivery system and can focus on the only thing left the carburetor.
What you all think?
One other question. I know for made 2 timing pointers on the drivers side; one cast and one bolt on. Did they use the same balancer? If not I might be running to retarded which would explain the running hot and rich at an idle.
Is this reason correct?
Did you say you tried another carb? I had a new 780 Holley but had it stored for 2 years, put it on my new rebuilt motor and went through a lot of the stuff you have done. My plugs were filing out. Took my carb to a repair shop, an old drag racer, had it rebuilt and it did the same thing. After going through some more trial and errors, I replace the carb with another one I had, still the same problem, decided to bite the bullet and bought a new eldebrock carb and it that fixed it. My car is a 70 mach I, 351 C motor.
Just my 2 cents worth. Good luck, I sure feel for you!
Your fuel is hot and is boiling away, hence your empty filter and 3 psi at idle.
So, whenever you want to replace something, ask yourself "What does this have to do with my fuel getting hot enough to boil away?" Would a bad carb boil your hot fuel away before it's even reached the carb? A coil? Ignition box? Intake gasket? High/low float levels? Give me a break.
What will shooting gas into a can prove to you? Your car already runs so that test is pointless. Your empty clear filter is already telling you there is no gas when it is hot. Your pump can shoot fuel into an empty can at .5 PSI, so what does that tell you? Nothing.
Answer these before you go on:
Does your fan blow hot radiator air directly on the fuel line?
HAve you tried watering down the fuel line when it is at 3PSI to see if it creeps back up?
Are you trying to ignore the very high possibility that it is a simple vapor lock problem that can be fixed for just about free?
don't forget that he can also see rust in that clear fuel filter too. so he could have a semi clogged fuel pickup sock, rust blockage in the line or in the fuel pump that doesn't show up until the car runs for a while, if it's the fuel pump it also may not show up until the pump gets hot too.
the easiest way i know of to see if it's a vapor lock issue is to put some wooden clothes lines on the metal fuel lines in the engine compartment about ever 2-3", if the problem subsides it's definitely a vapor lock issue, if it doesn't it "could" be something else entirely but the clothes pin trick almost always works...i'd say about 90% of the time. you could also try clamping a small piece of wood to the fuel pump as well, anything to try to dissipate the heat.
i'd stil recommend at least getting the fuel tank flushed and sealed or just flat out buy another tank, rust in the tank is no bueno mi amigo....no good at all.
it could also be as simple as one of the rubber lines between the tank and the pump has a small hole in it, usually on the topside of the hose, that is pretty well sealed up when it's cold but when it gets hot from engine and exhaust heat blowing back on it it opens enough to cause the pump to suck air.
The clothespin myth needs to die. Explain how wood dissipates heat. Even if you clamped some heat-dissipating material around the line, all that would happen is the hot air surrounding the line would be absorbed into the fuel, making things worse. You're assuming the fuel begins at a higher temp than ambient - it isn't. The heat needs to be blocked from reaching it, not dissipated out. If the fuel temp is indeed higher than ambient then that's the problem that needs to be fixed.
Any "fix" that clothespins might have done (besides pure coincidence) was most likely due to the pins creating air turbulence around the line but again that won't help if the air blowing on the line is coming right from the radiator fan's outlet.
This is getting goofier by the minute. Ron's right about being reasonable about you're troubleshooting. If you aren't getting gas to the carb, then you can rule out the coil, timing marks, radiator, carb, tire wear, alien invasions, the latest Presidential election polls and anything else except the gas tank, the line feeding the fuel pump and the fuel pump. Period. Carbed cars are unbeleiveabley simple and require only minimal fuel flow to live happily. If you see rust in your filter, junk the tank and buy another one. I know that sounds extreme, but how much is a brand new, US-made tank? $90? How much have you soent so far? Quit screwing around, buy a new tank at the bare minimum, and I'll bet you're mysterious problem goes away. Also, in my experience, vapor lock usually only happens on or around the pump-to-carb line. How could it happen on the tank-to-pump line? There is no heat anywhere near that line, and heat is what causes vapor lock. Also, I have never experienced vapor lock with a running engine. I have had problems after shutting a car off in hot (90+) weather. When that happens, heat soaks the carb and gas line, restricting fuel flow until the carb itself cools off. No matter what you do, you need to do a little cause-and-affect thinking rather than simply replacing ignition parts one day and fule system parts the next.
ITs all been on suggestions. Electrical parts get iffiy at higher temps. The ignition parts didn't cost me anything, because I always keep spares. Mallory parts are a special order at my local speed shop so I keep 1 extra in my garage.
My fuel lines are rubber not metal and from my understanding that was supposed to stop vapor lock.
I have been askign questions regarding ignition products, because my thinking was I had 2 problems fueling each other. Maybe a faulty ignition part, incorrect timing, or something causing a retarded ignition pulse. This would cause the engine to run hotter then it had in the past. The radiator, dual fan combo can dissipate lots of heat so it keep the engine cool until the next problem (yet to be discovered) started.
I am a teacher so I can only work on it at home. I drive about 1.5 hours to get home so I usually get home around 6pm. Its usually cooled off and i have to block off the radiator to get it to heat up and act up. In the past I tried something and had to wait until I was driving home the next day to see if it worked, because early morning and late night it runs fine. The temps rarely got over 180.
I am going to try the water trick to see if the pressure goes up, and try using my gas can to feed the pump. You never know and both these are free.
I know what the problem is its just solving it is been the issue.
It runs hot and is boiling the gas.
the clotespin does work, you're thinking is sound right up to the point where you say that the fuel begins at higher ambient temp but really doesn't. the clothespin is removing heat from the metal fuel line not the fuel. what happens is the fuel line will absorb engine heat and heat the fuel by means of contact, in some cases enough for it to boil when it gets introduced to the fuel bowl and is allowed to expand , thus causing vapor lock. the wooden clothes pin will dissipate that absorbed heat from the fuel line thus not allowing the fuel to get hot enough to boil once it hits the fuel bowl.
as redneck as it seems the clothes pin trick can and does work but only as it applies to the fuel line itself adding enough to heat to cause the fuel bowl, in this case since the fuel pump is so hot and he is using rubber fuel line between the pump and the carb the clothes pin trick won't work since the rubber will dissipate about as much heat as the clothes pin will. i guess i missed the part where he said he was using rubber to the carb.
this trick does work and i know it does. i had a 78 dodge monaco with the 360 PI motor in high school and it would vapor lock just about every day in the summer heat with the ac blowing full blast, after i put 3 or 4 clothes pins on the metal fuel line it would no longer vapor lock and just to test that it was actually due to the clothes pins i would remove them and drive it for a few days and it would start doing it again almost immediately, put them back on and it would quit again, finally i just left them on and it never vapor locked again afterwards.
I wouldn't use rubber gas line in any length at all, regardless of intent. There's a good reason that any NHRA inspector will not let your car on the track if it has more than 12" of rubber throughout the entire system; it's dangerous. I can understand your frustration at seeing this problem go on for so long, but here's my personal troubleshooting method and so far it has worked. If you suspect timing problems, you don't need a timing light or accurate marker to get it surprisingly close. I'd simply add timing until it pings under acceration, then back it off a bit. That sounds overly simple, but it works very, very well. My experience is that engines typically overheat and act sluggish when they have retarded timing. Unless it's pinging, you don't have too much timing. Now would be a wonderful time to mention that if you have trouble getting the timing right, or if the car runs badly at steady speeds, you could have a bad vacuum advance canister. Other than that, there simply isn't a whole lot that can exhibit the symptoms you're seeing. Ignition typically works, or it doesn't. Also, what do your plugs look like? Plugs are like a glimpse into the heartbeat of your engine. White plugs mean the ignition is working fine, but the fuel system is causing a meltdown. Wet plugs that smell of gas mean either a sticky float (or misadjusted float), too rich a carb, or a quircky choke. There's lots on plug reading elsewhere, but you get the idea, plugs are a way to see roughly what;s going on internally. But not one thing I've mentioned so far has even a remote effect on fuel pressure, and low fuel pressure is your problem. You can swap coils until your social security checks start coming in, and it won't have the slightest effect on fuel pressure. Period. It's like trouble shooting your TV for three months, carefuly analyzing every chip and diode inside, only to find out it's unplugged. If there's no electricity, nothing else matters. Same with your car, no gas, no fire, no fire, no go. Solve the problem you can see with your own eyes first, then worry about what you THINK the problem might be.
Well I tried the water on fuel hose and well it made the pressure go back up. So I can now assume hopefully rightfully its vapor locking.
Now here is the question why the hell, besides it started about a month before the warranty was up, did it start vapor locking when it ran fine for 2 years 11 months and 10k miles?
I had stainless steal fuel lines to start out with I went to rubber thinking the stainless steel was like coating a potato in alum foil.
I messed with timing and air fuel ratio when it was 210 and got the miss out, but not the throttle hesitation. The temps still continued to climb I shut it off at 230. IT wasn't boiling over though and the hose temperature never went over 195 on the top hose
OK there is so much scattered info here about your car so forgive me if I forget a few details.
The hot fuel line probably started happening around the time you started overheating, if it is overheating in the first place. The hotter air coming from the radiator is being blown by the fan onto the fuel line, or is it? I didn't see you answer that question. If it is, make a temp shield out of aluminum foil from pump to carb. Don't tightly wrap the line, just wrapped around the whole length loosely as if you don't want to ruin grandma's casserole, you want an air gap in there.
Your temp gauge accurate?
No crushed lines under the car?
You said new fuel pump, but new when? With the motor or after the stutter problem? What part # edelbrock pump is this so I have some idea?
the running like crap and hot came around the same time. If I remember right the same time on my way home in traffic.
I have 2 temperature guages, Original and a Sunpro electrical. I also have 2 electrical temp sensors stuck in the upper radiator hose and the lower radiator hose. I use a digital temperature guage used in electronics to check the temps. I also used a laser gun. When sun pro reads 200 water is about 190 and upper hose around 180. The original guage is in the middle.
I check for crushed lines, rusted lines, and pressure tested them with over 120 psi. I also held 30 psi pressure in the steel line over night and it held.
Fuel pump was replaced after installing a regulator and liquid guage. After this installation I discovered the fuel pump was not providing enough pressure above idle. dropped to 3-4. I then uninstalled regulator and installed edelbrock fuel pump.
So both problems kind of came at me at once. I know its running hotter then this exact setup did for 3 years. I just have checked everythign and I am totally lost. I did take it to a local tune shop and they took a look at it and then gave up after the temps kept climbing even with their shop fan.
They did a cranking pressure test. average was 126 and leak down was excellent in all cylinders. and They did say it was running way to rich, but then decided to lean out for no reason.
I saw you have both a pusher and a mechanical fan. What mechanical fan do you have on there?
As for the timing pointers, best you can do is find TDC on #1 and make sure it's zero on the balancer. Mine slipped 4-6 degrees but it's an original piece. If you think it's retarded, advance it 2 to 4 degrees and see how it works out. Going out for a test drive with too much advance won't hurt you, it'll either be hard to crank and/or ping under acceleration if you go too far. Just remember to set it back so you're only trying one thing at a time.
mechanical is a perma cool stainless steel flex fan. It was the only one that was actuall flat up front and allowed me 15/16 clearance from the radiator.
Do flex fans wear out? It still moves a good quantity of air.
I did advance the timing to about 14-16 and the rpms dropped less when in gear and with the a/c on. The bogging at 200-210 is still there. tomorrow I am going to try a remote gas can to eliminate a clogged pickup, and I also purchased a new factory replacement fuel pump just to see if the pump was taken out by the heat if the remote gas can doesn't solve the problem.
Here’s is a recap summing up all the questions asked regarding my possessed car.
5.0 - 34k miles on rebuild motor.
unfortunately the cobra cam was replaced with the explorer cam by Ford.
comp 900 distributor MBI
Bosch 8mm wires
Sparkplugs autolite 26s
edlerbock rpm manifold
New intake gasket
edlebrock 1405 carb
edlebrock victjr fuel pump (first changed from standard edlebrock pump I though it was vapor locking)
Fuels filters before carb and fuel pump
Radiator fluidyne 3 core alum 1.25 per core
50/50 dex cool
13 lb cap
180 degree thermo
Perma cool stainless steel flex fan
14. spal pusher 1500cfm rating
fuel lines are thermal wrapped
Timing 15 degrees at 800 rpm 38 at 3,500
vacuum bounces between 21-22 at 850 rpm
idle in gear 660-690.
a/f ratio 12.5-13.5
Random temp readings
Fuel line 190
back of manifold 180
thermostat housing 210
top of radiator 170
bottom of radiator 180
fuel pump 190
fuel pressure drops when hot from 6.5 -4 psi (increases when you put water on it.
Bogs and stumbles when temp over 200 – Never done this before. If I rev it up it goes away for about 1 minutes then continues.
Some fine rust color powder in bowls.
I think I solved one problem. I replaced my fuel pump with a stock replacement and it held pressure at the higher temps. To morrow I am going to take it for a spin to see if that solved the hesitation. I guess I must have fried the fuel pump when I clocked it to install it.
I still have a problem where its running to hot. I bought a mr gasket 160 high flow thermostat. That 180 is holding temps at 190. I do know I have plenty of water flow looks like the damn rapids in the radiator
The instructions for reclocking the Edelbrock pump require you to hold down the rocker arm while tightening the bolts to seat the diaphragm correctly, otherwise it will be under constant stress. Says you will get erratic and/or low pressure otherwise.
Tried re-burping the system? Jack up the front to make sure all the air goes out the radiator cap.