I have recently gotten tired of dealing with what I assume is Vapor Lock in my 85 244 gl. When the outside tempurature is high (usually 95) plus and I have been driving for a while, my car cuts out then kicks back on then cuts out and kicks back on until I just push in the clutch and coast and the RPMs slowly drop off until its dead. I'll wait about five to ten minutes then it starts back up and will drive fine for a while until the temp gauge is back up to the middle then it does the same thing. When the outside tempurature cools off in the evening i have no problems whatsoever. Yesterday, when it did this and I pulled over to the side of the road and stopped the temp gauge went almost to the red. I have tried wrapping the fuel lines and rail in foil but it didn't change anything. One time when this happened the fuel rail was too hot to touch but that hasn't been the case every time. Both fuel pumps were replaced within the last 10k. Am I dealing with vapor lock or some other gremlin?

 

Vapor lock occurs with carb'd cars; FI cars can't really vapor lock. You're dealing w/ an electronic component overheating and failing. A common culprit is the fuel pump relay.

 

Can I test the fuel pump relay with a jumper from the left hand side of fuse 6 and fuse 4? Seems like that's what I am getting through some research but I don't want to eff anything up. I have a new relay on the way. but I am pretty tired of waiting on the side of the road in this heat. http://www.fcpgroton.com

Also, it sounds like if the relay fails it fails and the car doesn't run at all. I haven't seen anything on here that suggests intermittent failures? your thoughts swiftjustice?

 

Every FI 240 or 7 series I've had has had fpr failures until I bought new. Many folks will tell you one can open them up and reflow the solder. I've done it but still prefer new w/ a couple of spares in the glove box w/ an od relay. In my experience, the contact points in the fpr can burn up as well or fuse; yet another argument to buy new. For me, failure begins intermittently. Generally, the car has been running awhile (heat) and generally more often in summer weather. I've had them present as hot no-start after shut down. Also, die in traffic, coast to the shoulder and restart after 4-5 minutes and then not do it again for a day or two.
This is only my opinion...but I consider relays as periodic maintenance. When I buy a rwd FI Volvo, I very soon replace the od relay and fp relay whether they fail or not. I'm 56, live in Texas and don't like sitting on the side of the road. So, yes...they can indeed fail intermittently...
To determine if the fr relay is bad, you can jumper the 6 point plug it connects to. When looking at the relay plugged intro the conncetor, hold the relay so the clip on the side of it is to your left. Remove the relay and jumper between the left connector closest to you and the middle one on the right. If there are no faults in wiring or pumps, they should both be running non stop. The key can be off and the pumps will still run. Use a decent gauge wire as there is a fair amount of current..I carry a 12 gauge jumper for just such a case. Listen under the car for the inline pump. Remove the fuel cap to hear the lift pump. While not horribly loud, they should be unmistakable.

 

Nah, jumper away... as long as fuel is in the tank. Have you tested both pumps with that method? What Swift said is one to check the pumps, but what you were doing is another. BTW, when you jumper the fuses, you are bypassing the relay, so that does not test it. If you ever stall out and need to go, have an alligator clip around and jumper those two fuses. That should run the pumps and get you home...

 

Thanks guys. Come to think of it, the other day I had a hard time starting just thought I was letting off the key too soon. I'll keep a jumper in the car until I get the new relay. and for just in case situations after that.

 

So the car died again and I used the jumper from left hand side of fuse 4 to left hand side of fuse six. sure enough you could hear the inline pump running, however, she would not stay running. I listened for the in tank but couldn't hear for sure if it was running. It idled very rough then died when I gave it gas. I waited ten minutes with out anything running and the jumper disconnected, started up and drove the rest of the way home.

 

It sounds like the inline pump is overheating but you have to wonder if that's due to a intank pump failure. With the car off and the fuses jumpered, remove the gas cap and listen there, it sound be fairly high pitched.

 

So, you jumpered the pumps. Now did you have fuse 4 in place when you did this? If you did NOT have the fuse in place, you only ran the pump outside the tank because you jumpered the left side of fuse 4 (car should have still ran, maybe rough, but still ran). If you DID have fuse 4 in place, both pumps should have ran.
To test the in-tank pump, jump the right side of fuse 4 with fuse 6. Granted, you may hear it run, but this does not eliminate it as a possible problem. There is a little rubber hose between the pump and the metal sending tube that can deteriorate and crack, greatly reducing the pressure supplied the the pump outside the tank.
This brings me to another question. How much gas is in the tank, full, empty? An empty tank will starve the outside pump if the in-tank pump or hose is bad. A full tank might cover the problem, might not. How many miles are on the car? Are BOTH pumps original? In-tank pump issues can wear out an outside pump, might be what you are running into.

 

Guys...this confusion is why I always suggest jumpering at the fpr connector.
To the OP...what is being said is that even if the intank pump runs, it may not be supplying sufficient fuel to the inline pump. The small piece of rubber hose that links the pump to the hard line built into the pump/sender hanger can deteriorate and mix air with the fuel when under say, half a tank. Typically, a failed intank pump doesn't result in a no-run condition but rather a poor run condition. I've added a picture of the fuel sender hanger and pump. You can see on top of the blue pump the small piece of hose that can fail.

 

I just got the new relay in the mail and installed it. So I'll cross my fingers and hope I don't wait on the roadside in the 90 degree heat. I'll inspect the pump hose this weekend. Burn stains-- Fuse four was in place. The tank is between 1/2 and 3/4 full. but the truly only common issue with all the breakdowns is the heat. I had one just before empty and another just after full. usually though in the 1/2 tank range. The car has 279k. I have the notebook that the guy who owned it before kept, he changed both fuel pumps about 15k miles ago.

 

Hopefully it will be the relay! One thing I've run into is people using standard fuel line to connect the intank lift pump to the hanger. Standard fuel line can withstand constant gasoline exposure but the outside will dissolve into a gooey mess. It has to be hose specifically designed for immersion. So...if the relay does not help, that's what I'd look at. Also, the intank pump has a pig tail that enters the interior of the car and then has a connector. Check that connector as occasionally old pumps pull too many amps and can cause the connector to fail.

 

What grade is yours then? You buy a kit? Or did you go to the local hardware store...

 

Then it should be the relay, unless he did use the wrong hose in the tank, then that could have failed again. There is a way to test the delivery pressure of the in-tank pump though...

 

Every intank pump I've seen new in the box has a short length of the appropriate immersible type hose. Immersible is the key; lawn mower hose just won't get it.

As for testing the intank pump flow, I think an eyeball test is as good as any. I merely remove the feed hose from the back of the inline pump and bump the key. Be sure to have a catch pan and all flames extinguished. That tiny pump moves a LOT of gas when healthy!

 

So you are hoping they put the right hose in the box then...

 

Hope? Not really. I came to believe years ago that if I have time to hope, I have time to make certain. The fact is we stock AC Delco and AirTex pumps. AirTex uses Gates hose while ACD uses house brand. I've had pumps be mis-boxed and/or d.o.a. so I suppose there could be a run of wrong hose. Here's a link w/ part numbers...
Submersible Fuel Line Hose - Hose - Products | Gates Corporation

 

So a garden hose won't work?

 

Secretly, I always prefer McDonalds straws!

 

I pulled the intank to find out if the hose was bad. because the new relay didnt solve the problem. it looked like it had been put in yesterday. so i pulled the pump off and hooked it up to a battery, nothing but a click. so here's hoping that the new intank pump keeps us from overheating. another cross state trip today so we'll find out for sure. I dont mind gambling on hope when the for sure costs more money.