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| Vapor lock? https://slantsix.org/forum/viewtopic.php?t=5829 |
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| Author: | Daddio [ Fri May 23, 2003 5:27 pm ] |
| Post subject: | Vapor lock? |
I have what I think is a vapor lock problem on my 83 D150, which seems to occur intermittently, and only at startup. If it sits for 2 hours or more, it will start right up, only to stall out, then it won't come close to starting. Th fix is to pour about 1/2 pint of gas into the carb, then she'll start and stay running. (the engine runs flawlessly once it's running) Everything under the hood is new electrically (plugs, wires, etc) and I've installed a new fuel pump and fuel filter, plus I put an accelerator pump into the 2bbl. (looks like an old time chrysler filter except for a bypass line out the side) I tried pinching off the bypass hose, and it seemed to work for a while, but after about a week, the problem came back with a vengeance. My next attempt for a fix will be an old style fuel filter (I'll block off the return line) and mybe I'll replace te metal line between the filter and carb with a rubber hose. The problem ismuch worse when the weather is warm. Anybody else ever have this problem or find a cure? Thanks for any answers. |
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| Author: | oldstyle [ Mon May 26, 2003 1:43 pm ] |
| Post subject: | 68 dodge sportsman |
dadio i have a 68 dodge van and i too have hard starting problems hot. i have a 225 with less than 40,000 miles. I t has a one barrel carb with a petronics electronic igntion and a accell super stock coil. After installing the petronics i noticed a increase in starting in hot weather but it still is tough. example: after running in a 80 degree day ill shut off van and when it sits for a few minutes ill try to start it. now if i have to crank it for 5 revolutions and then depress pedel half way down it will start, but if i try to drive after starting it will stall. likewise if it fails to start on the 5 crank half pedel down method ill have a hard time starting. any sugustions will be appreiciated |
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| Author: | Eric W [ Mon May 26, 2003 11:20 pm ] |
| Post subject: | |
Here is a fix that a member here recommended to me 2 years ago. Remove the metal fuel line from the fuel pump to carb. Install a 90 degree fitting to the fuel pump (pointing up when installed), a straight one on the carb. Get some fuel injection fuel line from the auto parts store, and a METAL fuel filter. Run the line from pump to carb., installing the filter so it sits behind the alternator. All my hard starting problems went away when I did this fix. I also zip tied the line to the heater hose bracket that attaches to the valve cover, so that is the only place the line makes any contact with the engine. The F.I. fuel line is harder than regular fuel line, can handle more pressure. The fittings (I dont remember the dimensions) are brass, I used the barbed type on the carb. Well worth the time to do. |
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| Author: | Pierre [ Tue May 27, 2003 1:09 am ] |
| Post subject: | |
EFI fuel hose is superexpensive.. over $5 a foot from what I have found locally. Seeing that your mechanical pump only does what, 5psi or so, regular fuel line is just fine. The guy at napa told me the fuel hose he sold me for less then $1 a foot (SAEJ30R7) was rated up to 50psi. I have been running it with an electrical fuel pump that does 18psi before the regulator and nothing abnormal so far. You don't need a hose that can handle 100+ psi when you are only putting 5 through it. |
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| Author: | Eric W [ Tue May 27, 2003 10:56 am ] |
| Post subject: | |
I think the FI hose was recommended because of its resistance to heat. After 2 years on my car (well over 40K miles since installed) its still hard and flexible. Most fuel line seems to get "mushy" and cracked. I believe it was Dan the Red (?) that recommended this. He can explain better than me. Yes, my wallet was not happy with the price of the hose either. 
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| Author: | mighty mouse 63 [ Tue May 27, 2003 11:15 am ] |
| Post subject: | |
Mounted steel canister filter to orginal coil bracket (fits just fine) and sheathed the 5/16 fuel line in 1/2 heater hose and secured this to the alternator bracket with nylon ties and routed this to the carb. I use only regular fuel line as don't see the point of using efi hose when running 7lbs pressure. I replace all hoses once a year anyway as normal maintanance. |
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| Author: | bud L. [ Tue May 27, 2003 1:55 pm ] |
| Post subject: | ? |
Some of the hot start problems can be traced to a leaky needle & seat, and/or float problems. After the engine is fully warmed up, remove the air cleaner top and element, shut down the engine, and immediately look down the throat of the carb. Continue to watch for several minutes. If you see any wisps of vapor or smoke, you are probably witnessing 'pullover'. It is raw fuel overflowing, or being percolated out of the float bowl, and evaporating in the manifold. This can cause flooding, hard starting, and other associated problems. |
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| Author: | Pierre [ Tue May 27, 2003 2:24 pm ] |
| Post subject: | |
For those who insist on EFI hose for your carb... remember there is also a piece of rubber hose in line right around where the tranny pan is. There are actually two metal pipe pieces between the tank and the fuel pump. At least there was on my duster. Although it was coverd in undercoating it did leak a tiny bit so when I went to efi I replaced it with regular hose and used EFI hose clamps. Now EFI hose clamps on the other hand I think are worth it. |
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| Author: | Daddio [ Fri May 30, 2003 2:32 pm ] |
| Post subject: | found a cure!! |
At the recomendation of one o my buds who is a long time Chrysler owner, I cured theproblem by simply leaving the fuel cap very slightly loose. ot one problem since, and now I hve a great running and reliable truck. Thanks to all who replied, and please leave me your thoughts on the cure I've found. Tim |
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| Author: | bud L. [ Fri May 30, 2003 4:12 pm ] |
| Post subject: | ? |
you may have treated the symptom, but i don't think that is a long term cure. |
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| Author: | Pierre [ Fri May 30, 2003 4:24 pm ] |
| Post subject: | |
Don't they make vented gas caps? |
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| Author: | kesteb [ Sat May 31, 2003 8:09 am ] |
| Post subject: | |
If opening the gas cap "cured" the problem, then the gas tank does not have adequate ventilation. This means the steel line that runs from the evaporation canister has finally rusted shut. You will need to replace this line, or get a vented gas cap. |
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| Author: | SlantSixDan [ Mon Jun 02, 2003 2:54 pm ] |
| Post subject: | |
I am indeed the one who recommended replacing the metal pump-to-carb line with fuel injection hose. The SAE J30R9 hose is obviously overkill from a pressure perspective, but I use (and spec) it for a few reasons: It's much more resistant to heat, puncture, abrasion, fuel additives, hardening and cracking, and it does a better job of keeping whatever is inside it (fuel) cool. The price of this stuff is all over the map - I've seen it for $5 for an 18-inch section, but I've also bought it for not much more than $1/foot at NAPA. Even if it were only available at $5/foot, that's a critical line that passes over a hot exhaust manifold and runs near sharp-edged and moving stuff, so to me the one-time extra expense is worth the added peace of mind. As far as replacing it every year...sure, with the 30R7 hose, but not necessary with 30R9 because it doesn't harden or age nearly as fast. Parts and labor (how much is your time worth?) on a couple replacements of the 30R7 hose will add up to one 30R9 hose. My opinion only, there's no strict necessity for the better hose. I've never understood the logic(?) of clamping the fuel filter to the block. It's a surefire way to transfer engine heat to the fuel filter and thereby to the fuel. And I never had any success insulating the original metal pump-to-carb line, though I tried several different ways. Mostly the result was dumb-lookin' and ineffective. The hose replacement for the metal line works so well I quit trying to insulate the original line. I'll also agree with the poster who said that leaving the gas cap loose is the wrong way to do it; if it "fixes" the problem it's just masking a symptom; find and fix the problem. It's not safe to drive with a loose gas cap, and also costs you money in lost fuel (liquid and vapor). Fuel caps haven't had open vents since the early '70s when they went to what is called a "Pressure-Vacuum" cap with a one-way "gulp" valve that lets air freely enter as the fuel level drops, but a spring-loaded valve the other way so that fuel tank vapors CANNOT escape from the tank until a certain pressure is reached. If this valve gets clogged, starting problems can result. It's also worth checking the charcoal cannister - they do not last forever, and some of them have replaceable air inlet filters on the bottom. |
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